Pakistani volunteers rush an injured person to a local hospital in Karachi, Pakistan, Thursday, Jan. 24, 2013. A bomb planted in a hollow concrete block has killed scores of police officers and injured many in southern Pakistan, police said. (AP Photo/Shakil Adil)

Karachi - Twin bombs explosions on Thursday killed four people and injured nine others in Pakistan's financial capital of Karachi, officials said.

The bombs, which were both planted in a garbage dump, exploded one after the other in the city's impoverished Sherpao Colony neighbourhood.

“Three policemen were killed and three others were wounded in the twin blasts in Sherpao Colony,” Hashim Raza Zaidi, Karachi's administrative chief told AFP.

Hospital officials said that one civilian was also killed and six others were wounded.

“Four people have been killed in the twin blasts, three of them are policemen. There are nine others injured which include three policemen and six civilians,” Doctor Seemi Jamali, director of Jinnah hospital, told AFP.

“Among the killed, one is a senior official who went there to inspect the site,” she said.

Zaidi said that the victims were killed by the second blast when they rushed to the site after the first explosion.

“The remote control devices were planted on a garbage dump. The first explosion did not damage anything but when policemen and civilians reached the site, there was a second blast, which hurt them,” he said.

On January 10, Two suicide bombers killed 92 people and wounded 121 after they targeted a crowded snooker club in the southwestern city of Quetta, in an area dominated by Shiite Muslims from the Hazara ethnic minority.

Another security official termed the incident a terror attack.

“It was an act of terror. Further investigations are being carried out by police,” said a senior security official on the condition of anonymity because he was not authorised to talk to media.

In 2012, around 2000 people were killed in violence linked to ethnic and political tensions, in the deadliest year for the city of 18 million people in two decades.

Islamabad says more than 35 000 people have been killed as a result of terrorism in the country since the 9/11 attacks on the United States. - Sapa-AFP