By GREGORY KATZ
LONDON — British police made a “significant” arrest Saturday in the manhunt for suspects a day after the London subway was hit by a partially-exploded bomb and launched a heavily armed search of a home southwest of London.
The fast-moving inquiry into the subway blast that wounded 29 people has shifted to Sunbury, on the outskirts of the British capital, where neighbors were evacuated amid the police operation as a precaution.
A no-fly zone was established over the area to keep out small planes and drones as police moved in and police cordons were put in place to keep the public well away.
No details about the police search were released, but it came after the arrest of an 18-year-old man who is being held under the Terrorism Act. The man was arrested Saturday morning by Kent police in the port of Dover on the English Channel.
Dover is a major ferry port for travel between Britain and France — and it was not clear if the suspect was trying to board a ferry for France when he was taken into custody.
“We have made a significant arrest in our investigation this morning,” Deputy Assistant Police Commissioner Neil Basu said. But he warned that the investigation was ongoing and the terrorist threat level remains at “critical,” meaning that top British security services believe that another attack is imminent.
Basu’s comments suggested that other dangerous suspects may still be at large.
Police Commissioner Cressida Dick called the arrest “very significant” but said the public should still be vigilant.
The 18-year-old suspect hasn’t been charged or identified. Police say he was being brought to a south London police station for more questioning. Police haven’t said if he is suspected of planting the bomb or of playing a supporting role in a possible plot.
Authorities had increased Britain’s terrorism threat level to “critical” late Friday — the highest possible level — after a bomb partially exploded on a subway train during the morning rush hour.
Police are combing through closed-circuit TV images and have extensively studied the remains of the explosive device. Images from inside the subway car showed that it was contained in a bucket with wires hanging out of it and concealed in a plastic shopping bag.
The train hit by the bomber at Parsons Green station in southwest London had video cameras in each car, and the London Underground network has thousands of cameras at the entrances to stations and along…