The home of UCLA researcher was firebombed on Tuesday, marking the second attack at the same residence in less than four months, authorities said.

The incendiary device was placed under the front door of the home of Edythe London, a professor of psychiatry and bio-behavioral sciences and of molecular and medical pharmacology at the David Geffen School of Medicine at University of California, Los Angeles, who uses lab monkeys in her research on nicotine addiction.

According to FBI representative Laura Eimiller, the device “was ignited and caused damage to the property. No one was home at the time and nobody was hurt,” she said, the Los Angeles Times reports.

She added that no one has yet claimed responsibility for the event. However, London’s home was also vandalized in October 20. Back then, an animal rights activist group called the Animal Liberation Front claimed responsibility for the incident meant to stop her animal experiments.

“Violence has once again been directed at a UCLA faculty member who conducts research involving laboratory animals. These kinds of deplorable tactics have no place in a civilized society. UCLA is working closely with the FBI and other law enforcement agencies to bring to justice those responsible for this and other acts of violence against our researchers," UCLA Chancellor Gene Block said, according to the Times.

The same group also claimed responsibility for leaving an incendiary device next to a car at the home of a UCLA ophthalmologist in June 2007 and near the home of a UCLA psychologist in summer 2006.

UCLA’s officials condemned the attacks, saying that their research “is in compliance with stringent federal and university polices to ensure humane care. This kind of research has led to many new treatments and discoveries that benefit society,” Phil Hampton, assistant director of UCLA’s media relations department said, according to the San Francisco Chronicle.

No arrests have been made so far. The FBI and the Joint Terrorism Task Force are working with UCLA officials on solving the case. Rewards are being offered for information leading to the resolution of the cases.