JOHANNESBURG, South Africa (AP) _ One policeman died and another was injured Friday when unidentified attackers fired guns and hurled a grenade into their van.

The attack was similar to others against police and white civilians carried out by the military wing of the Pan Africanist Congress, a small, militant black group raided by police this week.

Police detained more than 70 PAC officials and seized documents and computers in the sweep, the harshest crackdown on blacks since President F.W. de Klerk came to power in 1989. Most of the detainees have been released after questioning.

The PAC threatened to pull out of black-white talks on ending apartheid because of the raids, but an agreement reached Friday with the government eased the tension.

Under the agreement, police will release three top PAC officials still in detention and return documents and computers seized in the raids.

The PAC agreed to reexamine its support of armed struggle by the Azanian People's Liberation Army, its military wing.

Police Maj. Joseph Ngobeni said two black policemen were driving to work in a marked patrol van just after dawn when a mini bus carrying seven attackers drove up alongside. The occupants opened fire and threw the grenade, which landed in the van and exploded.

The attack took place on the main highway between Johannesburg and the black township of Soweto. Ngobeni said the identity of the attackers was unknown.