Authorities in the United States have confirmed that an airplane has crashed in the El Cajon area of Southern California.

The San Diego County Sheriff's Department reported an indeterminate number of injuries on Twitter.

Streets are shut off, and deputies advise motorists to avoid the area, warning that the situation will take time to process.

According to CNN affiliate KGTV, the Sheriff's Department stated the plane was a Learjet, and police are unsure how many people were on board.

According to authorities, there was a fire that had been extinguished.

According to the Sheriff's Department, the Federal Aviation Administration (FAA) and the National Transportation Safety Board (NTSB) have been alerted and will investigate the plane crash.

"We are just helping with the initial response and road closures," the Sheriff's Department wrote to CNN in an email.

El Cajon is located approximately 25 kilometers east of San Diego.