A magistrate in the Matete district in the east of the capital told AFP that unknown gunmen attacked the court office last night, burning several vehicles parked on the premises.
He said one police officer was killed and another wounded in the assault, adding that three prisoners held at the compound were later found to be missing.
The magistrate said a nearby police station had also been targeted.
The raid comes three weeks after dozens of prisoners escaped Kinshasha's largest jail following a rebel attack on the facility.
The May 17 jailbreak was carried out by followers of Bundu Dia Kongo (BDK), a secessionist rebel group that rejects Kinshasa's authority and wants to set up a parallel state in the west of the country.
Another attack on a prison two days later saw 68 inmates escape a prison in Kasangulu, 40 kilometres southwest of Kinshasa.