Reports of 20 victims wounded in mass US shooting

At least one person opened fire at or near a state social services agency in the Southern California city of San Bernardino on Wednesday and as many as 20 people were wounded, authorities said.

Triage area reportedly set up after a mass US shooting. (Twitter/WKABC) Source: Twitter

The San Bernardino Police Department said on Twitter that it had "confirmed 1 to 3 possible suspects" and multiple victims in the shooting. The agency called it an "active shooter" incident.

The San Bernardino Fire Department said in a tweet that it was responding to reports of 20 victims.

A police spokeswoman told the Los Angeles Times that the suspects were heavily armed and possibly wearing body armor, and CBS reported that a bomb squad was on the scene, trying to defuse what was believed to be an explosive device.

A spokeswoman for the Los Angeles Field Office of the US Bureau of Alcohol, Tobacco, Firearms and Explosives said agents were heading to the scene.

The scene of a mass shooting at San Bernardino in California. (FILE)

It was not immediately clear if any suspects had been taken into custody.

The shooting took place at the Inland Regional Center, one of 21 facilities serving people with developmental disabilities run by the state, said Nancy Lungren, spokeswoman for the California Department of Developmental Services.

Television images on CNN showed people being evacuated from the building, their arms raised, as triage stations were set up outside. Police and SWAT teams were seen surrounding the building.

A spokeswoman from nearby Loma Linda Medical Center said the hospital was expecting patients momentarily. "We're all kind of on standby right now - it could be any minute," spokeswoman Briana Pastorino said

The social services agency is among regional centers throughout California that administer, authorize and pay for assistance to people with disabilities such as autism and mental disabilities.

On an average day, doctors at the regional centers would be evaluating toddlers whose parents have concerns and case workers meeting with developmentally disabled adults. Lungren said that the San Bernardino facility is one of the state's largest and busiest.

The shooting in California comes less than a week after a gunman killed three people and wounded nine in a shooting rampage at a Planned Parenthood clinic in Colorado Springs. In October, a gunman killed nine people at a college in Oregon and in June a white gunman killed nine black churchgoers in South Carolina.