San Bernardino, California (CNN)The hunt for one to three suspects was taking place near a San Bernardino, California, center for people with developmental disabilities, 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.

• "There are multiple casualties and confirmed fatalities," San Bernardino Police spokeswoman Sgt. Vicki Cervantes told reporters.

• Four adults have been transported to Loma Linda University Medical Center, and the hospital is expecting three more patients, hospital spokeswoman Briana Pastorino said. She did not describe the nature of the patients' wounds. Arrowhead Regional Medical Center has received eight patients, an employee who didn't want to be named told CNN.

• 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.