A small army of blood technicians clad in red T-shirts and holding posters, banners and pennants raised their voices yesterday afternoon outside the building at 7th and Spring Garden streets housing the American Red Cross' blood-donor center.

"Red Cross, double cross!" the employees chanted.

About 100 members of Local 5103 of the Health Professionals and Allied Employees began striking yesterday morning in a fight for contract changes regarding safety, pay, scheduling and staffing.

Union members also held strikes at six other locations across Philadelphia, in Willow Grove and in New Jersey.

"We don't want to be out here," said union member and donor-collection assistant Marisol Homs, 30, of Northeast Philadelphia. "We didn't ask for this; we just want a fair contract."

Discussions between HPAE and the Red Cross ended Monday night without an agreement, said Jeannemarie Otersen, HPAE's public-policy director.

Strikers said they fear for the safety of those from whom they draw blood, but Red Cross spokesman Anthony Tornetta said that blood donations are safe and that he did not anticipate a blood shortage if the strike continues.

"If [the strike] does impact blood supply, we have the ability to go to one of our regional banks," Tornetta said, standing in a nearly empty blood-donation center.

As Tornetta spoke, the doors of the blood-donor center were locked behind him. One employee was inside, taking blood from a man who wished to donate platelets.

Tornetta said those wishing to donate blood should call 1-800-RED-CROSS before traveling to a facility.