Pakistani police say a bomb attack has killed seven officers in the southern city of Karachi.
Police officer Rao Anwaar says the bombing Thursday morning also wounded nearly 33 other policemen.
He says a van struck a bus the officers had boarded moments after it had left a training school in what appeared to be a suicide attack.
No one has claimed responsibility.
Pakistan's business hub, the port city of Karachi has long been a center of political, militant and sectarian violence.
The assault is latest in a series of attacks at a time when Pakistani government is trying to strike a peace deal with local Taliban.