WASHINGTON - A woman with a handgun opened fire on Thursday morning at a US Maryland distribution center, killing three people and injuring three others before taking her own life, local police said.

The 26-year-old woman shot herself twice in apparent suicide attempts after opening fire at drugstore Rite Aid's distribution center in Aberdeen, Harford County. She worked there as a temporary employee, Harford County Sheriff Jeffrey Gahler said.

Rite Aid spokeswoman Susan Henderson told CNN that about 1,000 employees work at the facility "where products are received and processed for delivery."

"The shooting happened adjacent to the primary building, "Henderson said.

One day earlier, at least four people were injured in a shooting at a judge's office in Fayette County, Pennsylvania. The shooter was reportedly dead on the scene.

The Fayette shooting came just hours after a gunman opened fire on Wednesday morning at a Wisconsin software company, wounding at least three people before being killed in a shootout with police.