A rocket hit the administration building of a provincial legislature in southwestern Pakistan, creating panic but causing no casualties, police said on Saturday.
No one claimed responsibility for Friday's attack on the Balochistan Assembly in the city of Quetta.
Investigator Wazir Khan said police had traced the area from where the rocket was fired, and had detained some suspects.
The assembly session had been adjourned an hour before the attack.
Balochistan has been the scene of scores of rocket and bomb attacks in recent years, most blamed on ethnic Baloch nationalists who are angry at the government's military and economic development plans for the province.