An explosion hit a bus stop in the Russian city of Voronezh (search) on Monday, wounding two people a week after a blast at a bus stop in the same city killed one, a local security official said.

A duty officer at the Federal Security Service (search) office in Voronezh said a 30-year-old woman was injured as she drove by the blast.

The explosion blew out windows on passing cars and on some nearby apartments, NTV television reported.

The local prosecutor's office opened a terrorism investigation into the blast, but there was no immediate indication of who the suspects might be.

On July 19, a bomb with the explosive equivalent of two pounds of TNT went off in a waste container near a bus stop in the city 300 miles south of Moscow. That blast occurred at roughly the same time — 8:15 a.m.

The ITAR-Tass news agency reported that a similar explosive device — loaded with bolts and screws — exploded in the city in February.

A series of explosions blamed on Chechen rebels and their supporters has plagued Russia in recent years. However, criminal and commercial disputes also sometimes spill over into violence.