Police acting on what they called specific intelligence shot a man during a raid on a house in east London early Friday and later arrested him on suspicion of terrorism.

The injured man, 23, was taken to a nearby hospital with injuries that were not life threatening. Another man, 20, was arrested at the house earlier under the Terrorism Act and was held at the high-security Paddington Green police station.

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"An examination of the officers' firearms confirms that a single shot was discharged in circumstances which are currently under investigation," said Deborah Glass of the Independent Police Complaints Commission.

She declined to say whether the shooting victim had been armed.

Police declined to describe the nature of the intelligence that prompted the raid, and said an examination of the house could continue for several days.

"Because of the very specific nature of the intelligence, we planned an operation that was designed to mitigate any threat to the public either from firearms or from hazardous substances," said Peter Clarke, head of the Anti-Terrorist Branch.

"Some officers were armed, and others equipped with protective clothing," Clarke said in a statement released by Metropolitan Police.

Jenny Jones, a member of the Metropolitan Police Authority, told British Broadcasting Corp. radio that "we have been told that people are going in and out wearing chemical protection suits and radioactivity protection suits."

Witnesses said police quietly moved into the racially mixed neighborhood before dawn, and they described seeing a man wearing a bloodstained T-shirt being carried out of the house.

Two other people in the house at the time of the raid were treated at the hospital, possibly suffering from shock, a police spokeswoman said on condition of anonymity in line with departmental policy. Both people were released.

Neighbors said a man, a woman and their four teenage children lived in the raided house. Some said the family had lived there for years.

"My parents heard the commotion and said there were police outside so I went around to the window and there were loads of police and loads of vans," said Dimple Hirani, 21. "I saw loads of police in special uniforms coming out of the van. They had special gloves and special equipment."

Police said officers executed a search warrant under the authority of the Terrorism Act in a raid described as "intelligence-led."

Shopkeeper Salim Mala, 42, said residents were a mixture of Bengalis, Pakistanis, Eastern Europeans and Britons.

He said when he arrived for work in the morning the streets were sealed off. Plainclothes police and officers wearing protective suits were combing the area.

The raid followed discussions between the Security Service, the police anti-terrorist branch and biochemical experts from the Health Protection Agency, police said.