Karachi, Apr 21 (Agencies): At least 14 people were killed and several wounded in a bomb blast in Pakistan's biggest city of Karachi on Thursday, police said.

"It was a planted bomb. We are gathering details," police official Saqib Sultan told Reuters.

The explosion occurred within the compound of a building in Ghasmandi area in the old quarters of Karachi.

A gambling den is located in the ground floor of the building, local residents said. Express 24/7 news channel reported that the blast was part of a fight between two gangs to control the gambling den.

Officials at the civil hospital said they had received 10 bodies and over 30 injured.

Six of the injured were in a serious condition, they said. A large crowd gathered at the site of the blast as local residents helped transport the injured to nearby hospitals.

Security forces cordoned off area shortly after the blast, which was heard from several kilometres away.

Footage on television showed the injured, many with bloodstained clothes, being taken into the civil hospital.

No group claimed responsibility for the attack.