The state of Minnesota has updated its driving manual with instructions for motorists with firearms and police officers who pull them over in hopes of preventing deadly outcomes.

Valerie Castile, whose son Philando was fatally shot by police officers even after he disclosed he was carrying a weapon during a traffic stop, helped lead the effort to draw up the new standards. She and law enforcement authorities unveiled the new Minnesota Driver's Manual on Monday, the fourth anniversary of his death.

"This information can save a lot of lives," Castile said at a news conference at Department of Public Safety headquarters to announce the changes. "We all need to be on the same page. We need to know what to expect from one another. At the end of the day, we all want to go home."

According to the new instructions, drivers carrying firearms during a traffic stop in Minnesota should keep their hands on the steering wheel, tell officers they have a weapon and say where it is.

Officers in return should greet the driver, ID themselves and specifically state the reason for the stop.

Above all for traffic stops where weapons are present: Everyone should stay calm.

"We all should expect respect," said Booker Hodges, an assistant commissioner of the Department of Public Safety.

Past editions of the manual featured general guidelines on how both motorists and law enforcement should handle traffic stops. But it was recently updated for the first time in many years by a working group that reviewed deadly force encounters and came back with 28 recommendations aimed at reducing them.

Valerie Castile was at the forefront of the process, which involved mental health professionals, law enforcement, advocacy groups and members of the community.

Public Safety Commissioner John Harrington said being stopped by a law enforcement officer can be a stressful experience. But knowing what to do and not do will help ensure that a simple traffic stop doesn't go awry.

"Hands are what kill in this business," Harrington said. "One way to reduce danger is to have a clear understanding of what should happen during a traffic stop. Effective today, people will have the information."

The guidelines on page 40 of the manual tell drivers to give their full attention to the officer, to make no sudden movements, and to wait to search for personal documents until the officer gives the command. Drivers should turn on the vehicle's interior light if a stop is made at night, the manual says.

After greeting the driver and identifying themselves, the manual states, officers should ask for a driver's license and proof of insurance and check their validity.

New officers have been trained to follow the new guidelines, Harrington said. And current officers in law enforcement agencies across the state are being trained to follow the updated guidelines, he said.

"None of this will work if we don't work together," said Clarence Castile, Philando's uncle and a member of the working group. "The community and police must get on the same page and respect each other, and not be afraid of each other."