Maryland Gov. Larry Hogan signed an executive order Monday declaring a state of emergency and activating the National Guard because of violence in Baltimore, reports WBAL-TV.

Police officers were injured, stores were looted, and fires were set Monday evening as vandals ran through Baltimore.

Baltimore police Capt. Eric Kowalczyk said police are not speculating what the disturbances are related to, but are making sure people in the community and officers are safe.

"I know that the images people are seeing on TV are very disturbing. Our highest priority, our first focus right now is to protect the lives of our officers that are out on the street and the people that live and work in that area," Kowalczyk said.

Kowalczyk said they know officers are in harm's way, and are using tear gas and pepper balls.

"As the night goes on, you're going to see us using tear gas and other crowd control techniques so that we can have this end peacefully without any more injuries to our officers or any of the people that are in that community," Kowalczyk said.