Maine highway safety officials are urging drivers to slow down and move over when they encounter an emergency responder vehicle on highways.

The message, issued Monday, comes at the start of Crash Responder Safety Week.

Crashes involving motor vehicles are the number one killer of police officers on state roads and highways, officials say. First responders, including firefighters, emergency medical services and tow truck operators are also at risk when they respond to a crash or emergency.

“It’s more than just the law, it is also common sense and courtesy to help ensure our first responders are safe to perform their jobs on our roads and highways,” Lauren Stewart, Director of the Maine Bureau of Highway Safety, said in a statement.