ALERT: San Bernardino shooting: Police seek 1-3 suspects, reports of possibly 20 victims

(CNN)The hunt for one to three suspects was taking place near a San Bernardino, California, medical and health center where as many as 20 people were shot Wednesday, authorities said.

SWAT teams and the bomb squad were working to clear the buildings where the shootings took place.

[Latest developments, posted at 4:02 p.m. ET]

• The three suspects are believed to be armed with AK-47-type weapons, a local law enforcement official told CNN.

• Witnesses told police they saw three men with long guns, a law enforcement source told CNN. The source said the suspects got into a black SUV and drove away.

The bomb squad found a suspicious package on the second floor of a building and determined it is "not normal," the source said. They are going to handle it with a robot, the source added.

• A woman who works at a building where the shootings occurred texted her father: "Shooting at my work. People shot." The father told CNN affiliate KABC his daughter told him 10 to 20 people were shot.

• Loma Linda University Medical Center is expecting an unknown number of patients from the shooting, spokeswoman Briana Pastorino said. She said the extent of the anticipated patients' injuries is not clear.

• There are multiple buildings in the complex, CNN affiliate KTLA reported. SWAT teams are moving methodically through to clear them.

• The FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives were responding, agency representatives said.

• Wednesday's shooting occurred at the Inland Regional Center, a facility for people with developmental disabilities. It is unclear how many people were at the facility at the time of the shooting. The center's Facebook page says it employs nearly 670 people at its facilities in San Bernardino and Riverside counties, providing service to more than 30,200 people.

It aims to "work on a personal, one-on-one basis with people with developmental disabilities to make their lives better as they define it." No information is yet available on how many people were at the facility at the time of the shooting.

• The sheriff's department tweeted that there was an "active shooter in the area of Orange Show Rd/Waterman Ave near Park Center."