A U.S. Postal Service employee has been charged with attempted murder after police say she shot two of her coworkers at the main post office in Des Moines, Iowa, on Thursday morning, and investigators are still searching for a motive.

Jennifer Christine Pledger, 39, of West Des Moines, faces two counts of attempted murder, two counts of willful injury causing serious injury and one count of intimidation with a dangerous weapon, all felonies, Des Moines police said. She is being held at the Polk County Jail without bail.

Police were called to the post office at 1165 Second Ave. around 9:10 a.m. local time after reports of a shooting on the building's second floor, an area not open to the public, police spokesperson Sgt. Paul Parizek said. Witnesses reported 10 to 12 shots fired. Witness and victim statements indicate Pledger opened fire on a group of Postal Service employees, striking one woman, who fell to the floor; police said Pledger then stood above her and fired again.

Two women, ages 45 and 53, suffered gunshot wounds, and a 55-year-old man was injured in a fall while trying to escape, Parizek said. All three victims are Postal Service employees, and all three were reported in stable condition with no life-threatening injuries. The two women drove themselves to MercyOne Des Moines Medical Center, across the street from the post office, while the injured man was taken there by a police officer.

Pledger left the building before officers arrived at 9:13 a.m. and was arrested without incident at 9:21 a.m. on a bike trail east of the post office after witnesses pointed her out, police said. A 9 mm handgun was recovered where she was taken into custody.

Des Moines police are leading the investigation with assistance from the FBI, the Bureau of Alcohol, Tobacco, Firearms and Explosives and the U.S. Postal Inspection Service. No motive has been released. The shooting also prompted brief lockdowns at nearby schools and a hospital.