Updated

A 21-year-old man arrested over last week's London subway bombing was released without charge Thursday, British police said. Five other men remain in custody.

The freed suspect, originally from Syria, was detained outside a fast-food restaurant in west London on Saturday, a day after the rush hour attack on a subway train.

Thirty people were injured when a homemade bomb — placed inside a bucket wrapped in a supermarket bag — partly detonated on a train stopped at Parsons Green station.

The attack sparked a manhunt for the perpetrators and prompted officials to briefly raise the national terrorism threat to the highest level.

The suspects still being held include an 18-year-old from Iraq detained at the English Channel port of Dover on Saturday.

Three men were arrested in Newport, Wales, earlier this week and a 17-year-old was held early Thursday in south London.

None of the suspects has been charged, and their names haven't been released.