Twenty-one women have died in a stampede at a birthday celebration rally for an Indian politician in the city of Lucknow, local officials say.
The BJP will pay compensation to the families of victims
Thousands had gathered in a park for the birthday rally of Lalji Tandon, state leader of the Bharatiya Janata Party in northern Uttar Pradesh state.
Local officials said people had rushed for the handout of free saris.
PM Atal Behari Vajpayee flew to meet victims' families in Lucknow, where he is standing in elections next month.
"The prime minister has expressed shock and grief over the incident and has extended his heartfelt condolences to bereaved families," a spokesman told AFP news agency.
About 15,000 people had crammed into the small park, which was fenced in and covered by a tent.
One woman attending, Ketaki Devi, told the Associated Press news agency: "We came with the hope that we would hear [Mr Tandon's] speech. He celebrated his birthday and gave us death. I saw several women fall down. They didn't get up."
One of the organisers, Brijendra Yadav, said: "We tried to stop the distribution but before we could, everything went haywire and old women were trampled to death."
Local doctors said 28 people had been injured.
Sunita Verma, the local leader of the BJP's women's wing, said people had rushed to get their saris first, although there were enough to go round.
Bundles of undistributed saris lay near the stage and hundreds of sandals were strewn across the park after the stampede.
The BBC's Ram Dutt Tripathi in Lucknow says crowds have gathered at mortuaries as people try to locate missing relatives and identify the dead.
An inquiry has been ordered into the deaths.
A criminal case has been filed against the committee that organised the function and a police inspector has been suspended for alleged negligence.
Mr Tandon holds his birthday rally each year.
But he distanced himself from Monday's function saying it was not organised by him and he had simply been invited as a guest.
He said the BJP would give the family of each affected victim 50,000 rupees ($1,145).
The Chief Minister of Uttar Pradesh, Mulayam Singh Yadav, has also said his administration will try and offer compensation to the families despite election commission guidelines which bar any government announcements ahead of voting.
Voting in the general election is to take place in four main phases from 20 April to 10 May. Lucknow votes on 5 May.