London Subway Attack: U.K. police make second arrest

LONDON — British authorities have arrested a second man in connection with the rush hour attack that injured 30 in a packed London subway station last week, the Metropolitan Police Service said Sunday.

The 21-year-old was arrested in Hounslow in West London just before midnight Saturday, police said in a statement.

On Saturday, the Met announced it had detained an 18-year-old near the Port of Dover — a key ferry terminal between Britain and France — calling it a "significant" arrest.

"At this stage we're keeping an open mind around whether more than one person is responsible for the attack," Neil Basu, the senior national coordinator for counterterrorism policing, told reporters.

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Also on Saturday, officials raided a property in the county of Surrey outside London, and evacuated a residential address and surrounding homes. A search of the address remained ongoing as a precautionary measure, and there were no immediate reports of other arrests.

After the detonation on a packed subway car at Parsons Green Tube station in southwest London, Prime Minister Theresa May announced that the nation's threat level for international terrorism had been increased to critical, its highest level, meaning another terror attack may be imminent.

Hundreds of soldiers have been deployed at strategic sites around the city to free up police to hunt those behind the incident — the latest in a series of attacks in the country's capital.

Photos of the incident shared on social media showed a bucket on fire in the subway car, with wires apparently protruding from the plastic bag the container had been carried in.

ISIS made its customary claim of responsibility for the attack, without providing any supporting evidence.