Four people were hurt when a small plane crashed Sunday morning at the Pomona Fairgrounds in Southern California. The Los Angeles County Fire Department said the incident was reported at 11:10 a.m. when a single-engine plane crashed near the drag strip at the Fairplex for reasons unknown. Video captured the plane flying over the Pomona Fairplex before hitting several cars, an RV and then slamming into the ground near the grandstand at the In-N-Out Burger NHRA Drag Racing Finals. The races were temporarily stopped following the crash. The Brackett Field Airport is the closest airport to the crash, but it’s unclear whether the plane was taking off from there or arriving. LA County Fire personnel who were already at the Fairplex for the races were able to assist with the crash immediately. “Saw that the plane crash was happening in real-time, they initiated a call and having been on scene were readily available to render aid,” said Jonathan Torres with LA County Fire. One pilot and three passengers were on board the single-engine plane. Two were treated for moderate and two for minor injuries. “All four souls aboard the plane were the ones transported so no injuries to people on the ground,” said Torres. Crews worked quickly to contain the fuel that spilled from the plane and prevent any potential fire danger from surrounding cars and generators. The NTSB and FAA are investigating the cause of the crash. “The Federal Aviation Administration has been notified and investigators from the National Transportation Safety Board are on the way to conduct an investigation into the collision,” Pomona police said in a statement.