LONDON (AP) — British police are questioning two men after a homemade parcel bomb was sent to the headquarters of the MI6 spy agency, and another was found at a London postal depot.

The men, aged 52 and 21, were arrested in Wales on explosives charges and being held Sunday at a London police station. They have not been charged.

The Metropolitan Police said a suspect package was found Wednesday "at a premises on Albert Embankment" — the location of Britain's foreign intelligence agency. Another device was intercepted at a postal sorting office.

The force said the packages had the potential to cause injury, but no one was hurt.

MI6's fortress-like headquarters is a London landmark. In 2000, it was slightly damaged in a rocket attack by Irish Republican Army dissidents.