Undated (AP) _ Labor leaders and the elderly were among those mourning the death of Sen. John Heinz III, a Republican who had worked especially hard for them.

''This tragic event leaves all of John's friends with an unbelievable sense of loss and a new awareness of the fragility of life - even one as young and precious as his,'' said Elsie Hillman, a longtime Heinz ally and Republican National committeewoman from Pittsburgh.

Heinz, 52, was killed Thursday when his Philadelphia-bound plane collided in the air with a helicopter outside Philadelphia. Six other people were killed, including two schoolchildren on the ground.

As Pennsylvania's senior senator, Heinz fought against subsidized imported steel and for senior citizens' benefits, two big issues in his state. In the weeks before his death, he had crisscrossed the state gathering reaction to the pending federal transportation budget.

Gov. Robert P. Casey described Heinz as a ''warm friend'' who left behind ''a long and honored career of service to the people of our state and our nation.''

Heinz, among the U.S. Senate's wealthiest members, had invested millions of his own money in his campaigns and won three easy elections to the Senate.

He was the largest individual shareholder of H.J. Heinz Co., the international food company founded in 1869 by his great-grandfather.

''The guy had everything,'' said House Republican Leader Matthew Ryan, R- Del. ''You just can't tell what will happen in this world. It's not fair.''

Lynn Williams, president of the United Steelworkers, said: ''Sen. Heinz was involved in and actively led the fight for creating and saving jobs, improving safety in the work place, establishing sensible trade policies and many other initiatives to enhance the well-being of our total society.''

The National Council on the Aging called Heinz, who had been the ranking Republican on the Special Senate Committee on Aging, ''an articulate, forceful champion of countless good causes.''

Attorney General Dick Thornburgh, who was Pennsylvania governor for eight years, said he felt Heinz' death as a deep, personal loss.

''As native Pittsburghers and longtime friends, John Heinz and I shared the joys and challenges of public service together over the last 25 years,'' Thornburgh said. ''His tireless and compassionate advocacy of significant causes for the public good provide an example for all of us as Americans.''