MALIBU, Calif. (CNS) — A mountain lion who was being tracked by National Park Service researchers but was killed by a vehicle in the Malibu area in June was pregnant with four kittens when she died, officials said Wednesday.

According to NPS biologists, the cat known as P-54 and her four unborn kittens were all found to have rat poison in their systems, a common hazard for the lion population in the Santa Monica Mountains.

"This is the first time during our 20-year study that we've been able to test mountain lion fetuses for anticoagulant rodenticides," Jeff Sikich, a biologist with the mountain lion project at Santa Monica Mountains National Recreation Area, said in a statement.

"A primary goal of our work is to learn whatever we can about these animals and how their lives are affected by the urban landscape they inhabit," he said. "Unfortunately, we've learned that mountain lions are susceptible to rat poisons even before they are born. In this case, it is also unfortunate because the death of P-54 from a vehicle resulted in the loss of four other young mountain lions, two males and two females, that were about to enter the population."

P-54 was struck around 9:30 a.m. June 17 on Las Virgenes Road between Piuma Road and Mulholland Highway. According to the NPS, the 5-year-old lion had five types of rat poison in her system, while her four unborn kittens all had at least three rat poisons in their systems.

P-54's mother, P-23, was fatally struck by a vehicle in January 2018 on the same roadway, Las Virgenes, although further south. One of P-54's offspring, P-97, was fatally struck by a vehicle on the San Diego (405) Freeway near Getty Center in April of this year.