KARACHI, Pakistan

At least one person was killed and nearly a dozen injured in an explosion in Pakistan's commercial capital Karachi on Monday evening, police and health officials said.

The blast -- second in less than a week -- occurred in an apparel warehouse in the city's busiest southern business district, Sharjeel Kharl, a city police chief, told reporters.

TV images showed giant plumes of fire and thick smoke billowing upward from the warehouse as rescuers were shifting the injured to the ambulances.

A police van and several other vehicles were completely or partially damaged in the blast.

According to initial investigations, the bomb was planted in a motorbike parked outside the warehouse.

Investigators believe the police van could be the target of the blast.

No group has claimed responsibility for the blast.

An improvised explosive device blast had killed one person and injured another 10 in the downtown Karachi last week.

Karachi, home to 20 million people, has seen a surge in terrorist attacks in recent weeks.

Three Chinese nationals were killed in a suicide bombing at the University of Karachi late last month.

The outlawed Balochistan Liberation Army which has long been fighting for the "liberation" of southwestern Balochistan province, had claimed responsibility for the suicide bombing.