[Updated 5:24 a.m.] A military spokesman said 3 people have died due to the blast. The injured toll stands at 18.
[Updated 11:48 p.m.] Military spokesman Major Bilal Farooq said 21 Rangers were injured; 11 were evacuated to a hospital; 3 are in critical condition. He condemned the attack as a "cowardly act."
[Updated 11:24 p.m.] Javed Odho, a senior Karachi police official, that it was a suicide attack. A truck carrying more than 100 kg (220 lbs) of explosive material hit a gate of Rangers headquarter.
Among the 13 injured, 9 are ranger officials, 3 are passersby and the other was a policeman, Odho said.
[Posted at 11:20 p.m.] A car bomb exploded in Karachi early this morning, injuring 13 people and destroying parts of the Rangers headquarters, said a senior police official.
The Rangers are a paramilitary force assigned to provide security in areas of conflict.