In response, teachers at MacArthur High School called the police, fearful he had made a bomb. The boy, an aspiring engineer, was led away in handcuffs "for his own safety" and questioned.

Since news of his arrest broke, including a picture of him looking confused and upset in the restraints, social media outrage has been overwhelming.

Then US President Barack Obama stepped up the #IstandwithAhmed hashtag trending on Twitter by tweeting to him: "Cool clock, Ahmed. Want to bring it to the White House? We should inspire more kids like you to like science. It's what makes America great."

Mark Zuckerberg, the Facebook founder and chief executive, messaged to him: "Having the skill and ambition to build something cool should lead to applause, not arrest. The future belongs to people like Ahmed. Ahmed, if you ever want to come by Facebook, I'd love to meet you. Keep building."

Hillary Clinton chimed in, tweeting: "Assumptions and fear don't keep us safe – they hold us back. Ahmed, stay curious and keep building."

But Texas authorities seemed unrepentant about their treatment of the young student, who remains suspended.

Texas police have confirmed that they will not press charges, but have not apologised to him or his family.

Irving police spokesman James McLellan suggested to local station WFAA that Ahmed had not been forthcoming enough during his interrogation.

"We attempted to question the juvenile about what it was and he would simply only tell us that it was a clock."

This was because, as CNN has noted since, it was a clock.

"We have no evidence to support that there was an intention to create alarm or cause people to be concerned," Irving police chief Larry Boyd said during a press conference after news of Ahmed's arrest prompted national outcry.

Ahmed, a self-assured kid with thick-framed glasses and a serious expression, started at MacArthur High School a few weeks ago. He has a talent for tinkering – he constructs his own radios and once built a Bluetooth speaker as a gift for his friend – and he wanted to show his new teachers what he could do.

So on Sunday night, he quickly put together a homemade digital clock ("just something small," as he casually put it to the Dallas Morning News: a circuit board and power supply connected to a digital display) and proudly offered it to his engineering teacher the next day.

But the teacher looked wary.

"He was like, 'That's really nice.'" Ahmed told the Dallas Morning News. "'I would advise you not to show any other teachers.'"

During English class, the clock beeped, annoying his teacher. When he brought the device up to her afterwards, she told him "it looks like a bomb", Ahmed said.

"I told her, 'It doesn't look like a bomb to me,'" he told the Dallas Morning News.

But the English teacher kept the clock, and later in the day Ahmed was pulled out of class by the principal.

"They took me to a room filled with five officers in which they interrogated me and searched through my stuff and took my tablet and my invention," the teen said. "They were like, 'So you tried to make a bomb?' I told them, 'No, I was trying to make a clock.'"

But his questioner responded: "It looks like a movie bomb to me."

Ahmed told NBC-Dallas Fort Worth that he was taken to police headquarters, handcuffed and fingerprinted.

During questioning, officers repeatedly brought up his last name, Ahmed said. When he tried to call his father, Ahmed said he was told he couldn't speak to his parents until after the interrogation was over.

"I really don't think it's fair because I brought something to school that wasn't a threat to anyone," Ahmed told NBC. "I didn't do anything wrong. I just showed my teachers something, and I end up being arrested later that day."

Asked about why Ahmed was not permitted to call his parents while being questioned by police, Mr Boyd said he did "not have answers to your specific question" about the allegation.

In a statement to the TV station, Irving Independent School District spokeswoman Lesley Weaver declined to discuss the case, though she confirmed that a MacArthur High School student was arrested on campus.

"We always ask our students and staff to immediately report if they observe any suspicious items and/or suspicious behaviour," she wrote. "If something is out of the ordinary, the information should be reported immediately to a school administrator and/or the police so it can be addressed right away. We will always take necessary precautions to protect our students and keep our school community as safe as possible."

NBC-DFW reported that a police report released on Tuesday cites a "hoax bomb" incident, listing three MacArthur High teachers as complainants against Ahmed.

Mr McLellan told the TV station that school officials were worried about the device.

"Clearly, there were disassembled clock parts in there, but he offered no more explanation than that," Mr McLellan said. "A lot of these details that the family and he have provided to you were not shared with us yesterday. He was very much less than forthcoming."

Mr McLellan told the Dallas Morning News that Ahmed never claimed the device was anything other than a clock. But school staff and police officers remained suspicious.

"It could reasonably be mistaken as a device if left in a bathroom or under a car," Mr McLellan said. "The concern was, what was this thing built for? Do we take him into custody?"

Ahmed's family said that the teen has been suspended from school for three days.

Speaking to the Dallas Morning News from his Irving home, Ahmed's father, Mohamed Elhassan Mohamed, blamed the incident on Islamophobia.

"He just wants to invent good things for mankind," said Mr Mohamed, who immigrated from Sudan. "But because his name is Mohamed and because of September 11, I think my son got mistreated."

That sentiment has rippled out in their community. Muram Ibrahim, a 15-year-old cousin of Ahmed's who was part of his middle school robotics team, said Ahmed's arrest makes her feel differently about going to school in Irving.

"It just shocked me that people could do this to him. He's a 14-year-old boy, and he's a genius," she said, recalling how her teammates used to call her younger cousin over whenever they needed help.

"I thought there's a lot of diversity at Irving [Independent School District], and I thought that it was different from other school districts," she said. "But I was wrong, and it makes me really sad that I'm wrong."

The Council on American-Islamic Relations said it will be looking into the case. Attorneys for the organisation, along with the Mohameds, told local TV station WFAA they plan to meet with the MacArthur High School principal and the Irving police chief on Wednesday afternoon.

"I think this wouldn't even be a question if his name wasn't Ahmed Mohamed," Alia Salem, CAIR's executive director for the Dallas-Fort Worth region, told WFAA.

Meanwhile, people online and off have rallied to the teenager's cause. The hashtags #IstandwithAhmed and #helpAhmedmake started trending on Twitter.

Muram said that she helped organise a protest at Irving schools, encouraging students to bring clocks to school in a show of solidarity.

As for Ahmed – he's a little taken aback by all the attention, Muram said. And still wrestling with the memory of handcuffs encircling his thin, 14-year-old wrists.

"It made me feel like I wasn't human," he said in a video interview. "It made me feel like a criminal."

Irvine's mayor, Beth Van Duyne, has backed the school and police for energetically investigating the threat posed by the eager student who built a clock.

"I do not fault the school or the police for looking into what they saw as a potential threat," Ms Van Duyne said.

"They have procedures to run when a possible threat or criminal act is discovered. They follow these procedures in the sole interest of protecting our children and school personnel. To the best of my knowledge, they followed protocol for investigating whether this was an attempt to bring a hoax bomb to a school campus.

"Following this investigation, Irving PD has stated no charges will be filed against the student. I hope this incident does not serve as a deterrent against our police and school personnel from maintaining the safety and security of our schools."

Ms Van Duyne is well known for speaking out against what she calls the threat of sharia in the United States.

- with the Washington Post

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