Palo Alto police on Thursday are searching for a mountain lion and cub.
The animals were spotted in a tree on the 1700 block of Webster Street around 6:20 a.m., according to police.
Although officers are on scene, the pair have not been seen again. Police are unsure if they are in the area, but are seeking help from the California Department of Fish and Wildlife.
"Our goal is to provide for the safety of our residents, and the mountain lions themselves too, as we work to locate them and safely extricate from the neighborhood," Palo Alto police said in a statement.
Resident Marcella Bernstein said she heard a noise Thursday morning in her backyard -- a noise she has not heard since her college days in vet school.
"(It was) a distinct, low percussive guttural growl consistent from what I've heard from lions. Sounds distressed," Bernstein said. "I saw one of the animals. The smaller one came down on a tree branch."
The Bernsteins said the neighbors' three dogs were outside and barking at the time.
Police also used a thermal imaging device to try and track the mountain lions. They did not see anything unusual.
"A mountain lion surrounded by people is a very real danger to public safety," Palo Alto Police Capt. Zach Perron said.
Perron said if found, the goal will be to tranquilize and safely relocate the cats.
In 2014, police were forced to shoot and kill a mountain lion in a residential neighborhood.
Parents earlier in the day were urged to drive their children to schools nearby.
Anyone who sees the mountain lions is called to stay away from them and immediately call 911.
For more information, visit the Palo Alto Police Department's Twitter Page.