The Saudi student, who was detained for “acting suspiciously” at the Boston Marathon finish line, has been described by his neighbors as a “quiet, devout Muslim who is a huge soccer fan”.

Detectives and bomb disposal officers raided the 20-year-old’s apartment last night in the Revere area of Boston and could be seen removing several bags of evidence, though he has not been charged with anything.

The Saudi student, who is studying English, is in hospital after suffering from serious burns and is said to be cooperating fully with police. He was tackled to the ground by a civilian who believed he was acting suspiciously. Several neighbors believed he had Anglicized his Saudi name to Jason.

The bombs had been placed in six-liter pressure cookers packed with ball bearings and nails and placed in black duffel bags, it was revealed today.

The Saudi student – who has not been named – said he had been at dinner with friends the night before and was at the marathon simply because he “wanted to see the end of the race”.

One of his two flat mates, Mohammed Bada, described him as a devout Muslim and a soccer fan who is from the city of Medina in Saudi Arabia.

He is attending an English language school in greater Boston, the roommate said, adding that he last saw him on Sunday.

It is not clear if agents found anything in the raid, but Revere fire officials said they were called out to support bomb-squad officers as part of the investigation of the “person of interest”.

Other residents in the smart 13-storey complex said three young men lived in a fifth floor apartment.

“There are a lot of rumors floating about. This is a building that has been packed with people from the Middle East in recent years – it is a very popular area with Saudi students,” said Gita Lopez, who lives in one of the adjoining six blocks in the complex that is known as Water’s Edge.

Staff at the building’s leasing office refused to comment on the suspect or his friends. But one said: “We are co-operating fully with the police.”

However, other neighbors pointed to Boston’s role in the September 11 2001 terrorist attacks.

Brothers Hamza and Ahmed Ghamdi spent their last four nights hiding out at hotels in nearby Cambridge before hijacking Flight 175 moments after take off from Boston’s Logan Airport.

At Boston’s Brigham and Women’s Hospital, investigators seized the Saudi student’s clothes to examine whether they held any evidence that he was behind the attack, which is being called the worst terrorist attack on U.S. soil since 9/11.

On Tuesday, police sources told the Associated Press the bombs were made from pressure cookers filled with metal.

When they exploded around 2.50 p.m., they left victims covered in as many as 40 wounds each and attacked their lower extremities, leaving many needing amputations.

Law sources told the New York Post that after the man was grabbed by police, he smelled of gun powder and said: “I thought there would be a second bomb.” Then he asked: “Did anyone die?”

The Saudi man was tackled by a bystander by the scene who thought he was acting suspiciously.

Investigators were seen leaving the scene with brown paper evidence bags, trash bags and a duffel bag.

A law enforcement source told CBS: “They see him running away from the device. Now, a reasonable person would be running away. But this person had noticed him before. This is a civilian – chases him down, tackles him, turns him over to the Boston police.

“The individual is being looked at [and] was suffering from burn injury. That means this person was pretty close to wherever this blast went off, but not so close as to suffer the serious injuries that other people did.”

Five minutes before the first explosion, officials said the hooded man attempted to gain entry to a restricted area but was turned away. Authorities say he may be a foreign national, based on his accent.

Other reports suggested one line of inquiry was an individual caught on camera before the attack carrying multiple backpacks into the area 20 minutes before the deadly blasts.

Separately, pictures of a man in handcuffs surrounded by law enforcement officials circulated Twitter on Monday evening. But authorities didn’t identify the man or say whether his arrest was related to the blasts or if it was the “Saudi national”.

“At this time, we haven’t been notified of any arrests or anyone apprehended,” a police spokesperson said.

He said the presence of law enforcement spotters on the roof at the start of the race also made the seasoned marathoner suspect police must have had some threat or suspicion called in.

But government officials deny this and say there were no warnings of any kind.

As police scurried to find leads that would lead them to the culprits, speculation grew that it looked more like a right-wing terrorist attack rather than al Qaeda-inspired extremism.

The two blasts on Monday went off almost concurrently near the Boston Marathon finish line.

Police initially said a third blast occurred at the JFK Presidential Library but later reported it as an unrelated fire.

Cell phone service was shut down across the area to prevent any potential remote detonations as police feared there were secondary devices.

Police were in a desperate race against time to find any additional devices and said the task had been complicated by the items discarded by spectators fleeing the scene.

Multiple reports were flooding in in the moments after the attack, saying there were devices reported outside Harvard and other sites along the marathon route. But today it was confirmed that there were only two devices.

Massachusetts General Hospital, where 22 victims of the bomb blast are being treated, was forced into lock-down for about two hours after a suspicious package was reported in the parking garage across the street.

Bomb sniffing dogs from the Rhode Island State Police, SWAT officers from the Boston police department and bomb squad officers searched the entire parking structure, floor-by-floor.

Authorities found one bag, but determined it was not a threat and contained nothing suspicious.

As the investigation continued into Monday night, all off-duty officers in the city were called back on duty and dog units were sent in to help the emergency response.

The scene of the blasts will remain cordoned off for at least 24 hours as forensic work continues.

Police were pleading with onlookers to head home over fears the dangers remained in the downtown area of the city.

NBC reported that the devices which caused the blasts were “small homemade bombs” as the FBI referred it as a “terrorist attack”.

Police departments across the country including San Francisco and New York have been put on heightened alert.

Today, a plane was brought back to the gate at Logan airport after two passengers on board were speaking Arabic and people grew concerned.