A Halloween night explosion shattered a window at a building housing offices for eBay's PayPal division, forcing the evacuation of dozens of employees.
PayPal spokeswoman Amanda Pires said Wednesday that the company had not received any threats but declined to comment on the investigation. The blast hit the first floor of the company's network operations center.
"We believe this is an isolated incident," she said. "We're working closely with local authorities. We have everything under control."
Business was not disrupted, but the complex was closed Wednesday and cordoned off by police tape. About 1,900 eBay and PayPal employees who work in buildings on the campus where the explosion occurred were asked to work from home or at another eBay campus in San Jose, Pires said.
No injuries were reported and no explosive device was found, but investigators determined the blast was deliberately set, Sgt. Nick Muyo said. Police had no suspects.
Investigators from the San Jose police and fire departments, the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives were investigating.
PayPal, which provides a platform for online payments, is a lucrative division of San Jose-based eBay Inc., generating some $350 million in revenue for the online auction company in the latest quarter.