Three people were killed and 18 others were injured Saturday when a bus rolled over in Pala Mesa, California, according to the North County Fire Protection District. The accident occurred around 10:30 a.m PST.

First responders arriving at the scene found the bus on its roof and in danger of sliding down an embankment, Captain John Choi of the NCFPD told CBS News affiliate KFMB. The bus needed to be stabilized before rescue crews could begin getting people out of the vehicle. According to Choi, the bus did not have seat belts. No other vehicles were involved in the accident.

All three people who died were adults, according to North County Fire Chief Stephen Abbott. The other passengers were taken to multiple hospitals with varying degrees of injury. Five were taken to Inland Valley Hospital, five were taken to Palomar Hospital and eight were taken to Temecula Valley Hospital, Choi said. None of the victims have been identified.

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Abbott stated one body is still trapped inside the bus, but all those requiring medical attention have been taken to the hospital. Everyone who was on board the bus has been accounted for, according to the driver.

"Given the terrain and the weather conditions, it's going to take a heavy wrecker and some heavy rescue type of operations in order to be able to move the bus," Abbott said.

Traffic was halted in both directions on I-15 following the crash.