Arson fires in Provo and West Jordan are clear signs that animals-rights groups in Utah are moving from rhetoric and vandalism to serious acts of violence that require vigilance on the part of law enforcement and the community, FBI officials said Friday.

"What we've seen is an escalation of violence," said FBI agent Ray Mey. "The individuals involved are trying to send a very strong message."

On Thursday, a fire at Brigham Young University's Ellsworth Farm caused more than $30,000 in damage but injured no one. Investigators say those responsible left behind the spray-painted calling card of a loosely organized group known as the Animal Liberation Front. The fire is the third time since May that BYU's animal husbandry center has been targeted, BYU Police Capt. Michael Harron said. Previous acts have include the release of rabbits and finches from their cages and the spilling of chemicals on equipment and building floors.

A fire last month at West Jordan's Stock Building supply torched lumber, several forklifts and caused an estimated $1.5 million in damage. ELF, or the Earth Liberation Front, a known sister group to the ALF, has claimed responsibility for that fire.

No one has been arrested for either event, although the FBI continues to investigate along with local police, fire departments, the Bureau of Alcohol, Tobacco and Firearms and Utah's Joint Terrorism Task Force, said Mey, who supervises the task force. The fires do not appear to be linked.

Both the BYU and West Jordan fires are being "looked at as an act of terrorism," Mey said, adding that law enforcement is concerned about the potential for loss of human life that could occur in fires and other violent acts.

National spokespersons for ALF and ELF are expected to appear at a July 15 rally at the Salt Lake City Library, using that event as a platform to continue to extol their views and philosophies, Mey said. National-level speakers from both groups are expected, although currently there is no indication that the Total Liberation Tour is intended to promote or spark any violence, he said.

Just the opposite, said Jakob Nyberg, the Salt Lake man who obtained a city event permit and has worked to make Salt Lake one of 13 stops the tour is making around the country this summer.