Gov. Larry Hogan signed the order Monday night at the request of the city. Cars and at least one store have been set on fire during a riot. Businesses are being looted in part of the city.
The riot started just hours after the funeral for Freddie Gray, who died after being injured while in police custody.
President Barack Obama is pledging the federal government’s help to respond to riots.
The White House says the Baltimore mayor updated Obama on the situation and that Obama told her his administration would provide assistance as needed.
The White House says Obama also discussed the rioting with Attorney General Loretta Lynch, who was sworn in hours earlier.
Obama and Lynch met in the Oval Office while violent scenes of rioting in Baltimore played out on television. Gray died April 19 after suffering a mysterious spinal injury while in police custody. The Justice Department and local authorities are investigating.
Additionally, the governor of Maryland says the National Guard is on alert and may deploy to help police with the looting and violence.
Gov. Larry Hogan says he wants the Guard on alert so they can deploy rapidly as needed. The governor readied the Guard as rioters set fire to cars and a business and looters raided several stores.
At least seven officers have been injured in chaos.
The Orioles game in Baltimore has been postponed because of safety concerns.
This is a developing story. Check back for details.