QUETTA, Pakistan (AP) — A speeding bus carrying wedding guests plunged into a ravine in southwestern Pakistan on Thursday, killing at least seven people, officials and rescuers said.

The cause of the accident near Quetta, the capital of restive Balochistan province, was not immediately known. An investigation was underway.

According to Wasim Baig, a spokesman for the health department, the bodies of the victims and 17 people who were injured in the accident were brought to a local hospital. Some of the injured were said to be in critical condition.

Road accidents are common in Pakistan, where highways and roads are poorly maintained and traffic laws are widely ignored.

In August, 32 people were killed in two bus accidents, one in Balochistan and the other in eastern Punjab province. Authorities at the time said both accidents were caused by the negligence of the drivers.

And earlier in August, 28 Pakistani pilgrims were killed in a bus crash in neighboring Iran while heading to Iraq.