Thursday, August 28, 2003 4:24 p.m. ET

By Michael Kahn

SAN FRANCISCO (Reuters) - Two homemade bombs exploded early on Thursday at Chiron Corp. headquarters, shutting down work at one of the nation’s largest biotech companies in what industry experts said might have been an attack mounted by animal rights activists.

Police said they had no suspects at the moment but a biomedical industry group, Americans for Medical Progress, said the explosions could have been the work of animal rights activists because the company uses animals for research.

Executives at the company, located in the Northern California city of Emeryville, have complained of being harassed by animal rights activists in recent weeks.

No injuries or major property damage were reported in the explosions, which took place at 2:55 a.m. PDT (5:55 a.m. EDT) and 4:10 a.m. PDT (7:10 a.m. EDT). A third device, packed in a five-gallon plastic container, was found in front of a third building at the Chiron complex by the Alameda County Sheriff’s Department and safely detonated.

"We have no suspects at the moment and nobody has taken responsibility" for the blasts, Sgt. LaJuan Collier, a spokesman for the Emeryville Police Department, told Reuters.

Collier said there were apparently no people in any of the three buildings at the time of the explosions.

Chiron spokesman John Gallagher said a number of executives have been harassed over the past month by animal rights protesters.

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The executives, whom he declined to name, have had rubbish dumped in their yards, slogans spray-painted on sidewalks, and protesters rallying outside their homes.

On the advice of law enforcement officials, the company over the past few weeks has stepped up security at its campus and warned its staff to be alert, he added.

While the company and police declined to say who might be behind the explosions, a spokeswoman for an industry group said the blasts were likely the work of activists who have targeted Chiron and other companies that use animals in research.

Barbara Rich, a spokeswoman for Americans for Medical Progress, added that the blasts came after an animal rights group, ShacUSA, named Chiron on its Web site as a so-called "customer of the week" to be targeted.

"It is no coincidence," Rich said. "Any company that uses animals for research is a target."

Kevin Jonas, a spokesman for ShacUSA, said the group had nothing to do with the explosions but simply serves as a clearing house for information for animal rights protests.

"On the surface ... it looks like (the work of animal rights protesters) but we are still waiting for confirmation," Jonas said in a telephone interview.

Chiron is the biggest employer in Emeryville, a community of 7,000 people located in the San Francisco Bay area between Oakland and Berkeley.

Bob Canter, president of the Emeryville Chamber of Commerce, said all 2,000 Chiron employees in Emeryville were told to stay home on Thursday. He said two of the city’s major streets were largely shut down amid the ongoing police investigation.