The Georgia Bureau of Investigation says the man who hijacked a Gwinnett County transit bus, killed someone aboard and led officers on a chase took the gun from another passenger.

The GBI said the incident started around 4:20 p.m. on Ivan Allen Boulevard in downtown Atlanta. The Gwinnett County bus picked up passengers, including Joseph Grier.

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Grier had been on the scene of a mass shooting at Peachtree Center hours before.

According to the GBI, Grier was engaging with passengers on the bus and got into an argument with another man. The other passenger, identified on the warrants as Ernest Byrd, pulled out a gun. Grier then took the gun from Byrd and started to threaten passengers with it.

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Grier then shot Byrd in the leg with his own gun and ordered the bus driver to drive away, according to the GBI.

Numerous law enforcement agencies then chased the bus as it traveled on I-85 north into Gwinnett and then DeKalb counties. During the chase, the bus hit multiple other cars and several police vehicles.

Officers flattened the tires on the bus, but it kept moving. A Georgia State Patrol officer then fired his gun into the engine compartment of the bus in order to get it to break down.

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The chase came to an end on Hugh Howell Road in Stone Mountain. Grier was taken into custody. Byrd was taken to a local hospital and pronounced dead. The bus driver was also taken to the hospital.

The GBI didn’t reveal the bus driver’s identity or current condition.

More than a dozen other passengers on the bus were able to get off safely.

The GBI will conduct an independent investigation of the use of force.

Grier is now facing more than a dozen charges, including murder.