LONDON, England (CNN) -- A second man was arrested Friday after a failed bomb attempt at a British restaurant, police confirmed.
Bomb suspect Nicky Reilly is shown with his face bloodied and cut after the explosion.
The alleged bomber was arrested Thursday but police believe he has a history of mental illness and fear others preyed on his vulnerability. A third man is helping with police inquiries.
Now police are searching for clues to what they say could be a terrorist cell in southwest England.
Nicky Reilly, 22, traveled by bus from his home in Plymouth, Devon, to the Giraffe restaurant -- a chain popular with families -- in Exeter, where he attempted to detonate explosives, police say.
They believe Reilly is a recent Islamic convert who had been "radicalized."
British authorities rarely name suspects before they are charged, but police are hoping the release of Reilly's name and picture can help them track his movements. That in turn could lead them to any accomplices or clues into the character and size of a what a police source said could be a terrorist cell in southwest England.
Tony Melville, the deputy chief constable of Devon and Cornwall Police, told reporters at a news conference at the scene Thursday: "Our investigations so far indicate Reilly, who has a history of mental illness, had adopted the Islamic faith," the UK's Press Association reported.
"We believe, despite his weak and vulnerable state, he was preyed upon, radicalized and taken advantage of," he said.
The incident happened in just before 1200 GMT Thursday. The packed city center was partly evacuated.
Reilly was described by friends as an "introverted loner" who adopted the Muslim faith and changed his name to Mohammed Rasheed last year, PA reported.
Reilly was arrested at the scene of the explosion, and suffered cuts to his eye and facial injuries after a device he was carrying exploded.
Another device found in the vicinity of the restaurant did not explode, police say.
Devon and Cornwall police say they are awaiting medical clearance to begin interviewing Reilly, who is under police guard in hospital.
Officers searched the home in Plymouth -- less than an hour's drive from Exeter -- which he shares with his mother for further clues on Friday.
No one else was injured in the blast, although 15 people were working in the restaurant at the time.
Witnesses said Reilly was seen entering the restaurant's toilets shortly before the blast but the explosion caused little damage.
In February, two mentally disabled women were sent into busy Baghdad markets, where they were blown up by remote control, an Iraqi government official said.