LOS ANGELES (AP) A child was among four people killed Wednesday in a shooting at a Southern California office building that left a fifth victim and the gunman critically wounded, police said.

The violence in the city of Orange southeast of Los Angeles was the nations third mass shooting in just over two weeks.

When police arrived at the two-story structure around 5:30 p.m. shots were being fired, Orange Police Lt. Jennifer Amat said. Officers opened fire and the suspect was taken to a hospital, Amat said.

Its unclear if the suspect suffered a self-inflicted wound or was shot by police. Police provided no details on the victims other than to say one was a child and a woman was critically wounded.

In a tweet, Gov. Gavin Newsom called the killings horrifying and heartbreaking.

Our hearts are with the families impacted by this terrible tragedy tonight, he wrote.