An unidentified assailant opened fire Thursday at a warehouse complex north of the US city of Baltimore, killing and wounding multiple people, authorities said.
A lone suspect was in critical condition at a local hospital, according to Harford County sheriff Jeffrey Gahler.
Police would not confirm reports that the shooter was a woman, but revealed that the suspect had not been shot by police.
"I can confirm multiple wounded and multiple fatalities," Gahler said.
US media reported that three people were killed and two others wounded in the incident, which erupted around 9:00 am (1300 GMT) at a distribution centre for the Rite Aid drugstore chain.
Gahler said the assailant apparently was armed with a single handgun "and no shots fired by any officers responding to the scene."