Phoenix shooting
© PhoenixPolice via YouTube
Phoenix police identified Isaiah Williams as a suspect.
Authorities in Arizona released security video Friday showing a gunman in tactical gear fire dozens of rounds in a motel parking lot last month in a shooting spree that left two people dead and several injured, including two police officers.

Investigators who processed the aftermath of the Aug. 28 incident north of downtown Phoenix found 200 spent rifle casings, five magazine cartridges, unused flash bangs and a Molotov cocktail, Phoenix Police Sgt. Vincent Cole said in a recorded statement.

Officers responding to the scene found the gunman had died by suicide, Cole said.

Cole did not identify a motive, but said the shooter, Isaiah Williams, 24, appeared to be firing "randomly" at buildings and cars in and around the parking lot.

The shooting began at roughly 8:30 p.m., when security video from inside an unidentified motel appeared to show the gunman emerging from a room wearing a helmet, a ballistics vest and knee pads.

He appeared to be armed with a rifle, and Cole said he was holding a Molotov cocktail.

Edited security video showed the gunman walking outside and immediately opening fire. In 911 audio included in the video, witnesses reported hearing what sounded like gunfire from an automatic weapon.

Another 911 caller reported seeing the gunman throw something at a window. Cole said he tossed the Molotov cocktail at a restaurant window, but the glass didn't shatter and the explosive didn't ignite.

At one point, the gunman could be seen firing at a white SUV driving into the parking lot, fatally wounding two occupants, Cole said. Others who were in the car could be seen fleeing the scene.

Authorities identified the fatally injured victims last month as Misael Arevalo, 36, and Karla Garzona, 44, according to NBC affiliate KPNX of Phoenix.

Efforts to reach their relatives Friday were unsuccessful.

Cole said a "couple" of other bystanders were injured in the shooting. In the video, an officer can be heard saying that someone had been shot in the ear and arm. The video also appeared to show the gunman shooter pointing his rifle at people but not firing.

When officers arrived, the gunman fired at them, Cole said. One of the officers returned fire but missed.

In body worn camera also released by the department, one officer could be heard saying, "I'm hit, I'm hit."

KPNX reported that they were expected to recover.

The incident was one of 473 mass shootings tallied this year by the nonprofit Gun Violence Archive, which defines the shootings as those with four or more victims of gun violence.

Last year saw a record 671 mass shootings, according to the archive, more than double the number recorded in 2014, the first year available in the group's data.