NEW DELHI, India (AP) _ A powerful explosion ripped through a crowded marketplace Tuesday, killing as many as 25 people and injuring up to 50, police said.

The blast appeared to have been caused by a car bomb, and two Kashmiri separatist groups jointly claimed responsibility, said Press Trust of India, a national news agency.

The groups _ the Jammu-Kashmir Islamic Front and Lashkar-e-Sajjad _ said the attack was aimed at forcing India's new government to cancel elections scheduled for Thursday and May 30 in war-torn Jammu-Kashmir.

The ballot would be the first in Jammu-Kashmir, the only Muslim majority state in mostly Hindu India, since militant groups began fighting for independence in 1989. Rebel groups have urged Kashmiris to boycott the election.

The Jammu-Kashmir Islamic Front also claimed responsibility for a bomb that killed eight people in another section of New Delhi early this year.

Tuesday's explosion occurred during evening rush hour in the upscale Lajpat Nagar Central Market, in a section of New Delhi where many people from Jammu-Kashmir live.

``Suddenly our window panes shattered and we thought our building was coming down, so I ran outside,'' said shop owner Subash Nischal, 47. ``I helped pick up two injured women from the street. I saw two others die there.''

He looked up at the burning buildings and shook his head. ``It must have been Kashmiri militants who did this.''

Firefighters needed three hours to douse the flames that roared through three commercial buildings.

The blast appeared to have been caused by explosives hidden in a parked van, said Dharmendra Kumar, deputy police commissioner in South Delhi.

As he spoke, policemen pulled battered bodies out of the buildings and mangled cars. The United News of India news agency quoted police as saying that bodies of many other victims might still be found in buildings and the basement.

The force of the blast blew out the windows of multistory buildings across the street, and shards of glass were sprinkled up and down the road. Pieces of one car flew 200 yards.

Prime Minister Atal Bihari Vajpayee, who took power last week after his Hindu nationalist party finished first in a national election, said no effort would be spared to find and prosecute those responsible.

At first, police said at least seven people were killed and 27 injured in the blast. Press Trust of India later reported that nine were killed and 50 injured. United News of India put the death toll at 25.

The explosion was the third in New Delhi in four months.

In January, a bomb killed eight people in a crowded marketplace in Old Delhi. The Jammu and Kashmir Islamic Front claimed responsibility, and police arrested two people they identified as Kashmiri militants.

On April 20, an explosion leveled a central Delhi hotel, killing 18 people. Police first blamed a bomb, but later said their investigation couldn't confirm that.