BERKELEY, Calif. -- Triggered by concerns over threatening emails, federal agents and UC Berkeley campus police have raided an activist center and internet cafe, seizing 14 computers.

UC Berkeley spokesman Robert Sanders would only confirm that threatening emails had been sent, but would not give out any further details.

"We were investigating threatening e-mails we tracked to computers there," he told the San Jose Mercury News. “The details of the e-mail are confidential because it is related to an investigation."

The target of the raid was the Long Haul Infoshop – a so-called "open activist space" – used by environmental groups and others such as the Berkeley Liberation Radio that has been open in its support of the tree-sitters who have taken over a controversial grove of oak trees on the UC campus.

The raid was conducted Wednesday by the FBI, UC Berkeley police and Alameda County Sheriff's deputies armed with a search warrant and according to the group’s web site took about 90 minutes to execute.

According to an activist at the offices, who only wanted to be identified as “B,” authorities may have been looking for information on animal rights activists or tree sitters.

Another member of Long Haul, which identifies itself as a nonprofit and runs a cafe and a library at the building where the raid occurred, said the agents and officers broke locks, shattered a wooden door and shuffled through multiple files.

"It looked like a breaking and entering," Long Haul member Chloe Smith said.

Smith said the raid was inappropriate because the Infoshop would have opened the gate for law enforcement and provided whatever they needed had they shown a warrant.

Authorities did have a warrant to seize the computers, Sanders said.

Smith said they came into the shop before it was open and that the raid lasted until about noon.

She responded to the allegation about the threatening e-mails, saying, "We have our computer area open all hours that we're open, and we keep that space unmonitored and many different people have come through here in the last 30 years."

The Infoshop is still open but all the computers are gone, as well as some hard drives and other documents.

UC researchers were targeted recently by two firebomb attacks on near the UC Santa Cruz campus.

The first incident occurred around 5:45 a.m. on Sept. 6 and ignited the porch of Professor David Feldheim's home in the west part of Santa Cruz. The researcher, his wife and their two children managed to escape down a fire ladder from a second-story window, according to police.

A short time after the firebomb damaged Feldheim's home, the car of another university researcher was firebombed outside a faculty housing area on campus.

Police said the incidents followed several attacks by "suspected animal rights extremists" since March 31, including the firebombing of a police vehicle. All agencies involved in the investigation were working to ensure the safety of others listed in animal rights pamphlets found at Caffe Pergolesi, located in downtown Santa Cruz, police spokesman Zach Friend said.

The pamphlets listed names and addresses of UC Santa Cruz researchers, and included threats toward them, according to police. The violence came after a list was found in a coffee shop with the personal information of 13 UC scientists, but police say it had several inaccuracies.

“There's three names and addresses where we know researchers do not live at these addresses and homes of families that are completely uninvolved with animal research could be targeted,” said Friend.

A $50,000 reward is being offered for information connected to the fire-bombings, according to police.

“B” told the San Jose Mercury News that several activist groups use their facility.

"All kinds of groups come through here, and I wouldn't be surprised if in the last 30 years an animal rights group came through here," said B. "But people who are on the road use our computers too. We have a bunch of computers and make them available to anybody who wants to use them."