A gun battle erupted in west Houston late Sunday morning, leaving two people dead and six wounded, and forcing authorities to issue a shelter-in-place order as residents prepared for Memorial Day festivities, authorities said on Sunday.

Two suspects were involved in the shooting, and one of them is believed to have shot and killed the other, Houston Interim Police Chief Martha Montalvo told reporters.

Later, a post on the department's Facebook page said the suspect was fatally shot by a Houston SWAT officer. There was no immediate explanation for the apparent contradiction, and police could not be immediately reached to clarify.

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The second suspect was wounded by officers and transported to a nearby hospital in critical conditions, the post said.

Montalvo said police did not know the motives behind the shootings and are seeking the public’s help.

"We are trying to piece all of this together," she said. "It’s still a very ongoing investigation."

The victims of the rampage, which unfolded over hours, included two wounded constables who were treated at a hospital and released.

The second fatality, described as a "citizen," was found by police in a vehicle. Montalvo said it was unclear what connection, if any, that person had with the suspects.

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Adding to the mayhem that gripped the area in the middle of a long holiday weekend, a fire broke out and destroyed a gasoline filling station near the shooting scene. Television video showed the charred station and fire crews still on the scene in mid-afternoon.

Montalvo did not address the connection, if any, between the shootout and a fire-ravaged Conoco gas station nearby. Fire officials could not be reached for comment.

The suspects also took aim at a helicopter hovering above the scene, and at least one shot hit the chopper.

"Obviously they had a high-powered rifle," Montalvo said. "We believe one of them had an AR-15.”

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The violence escalated after a patrol officer responded to the first report of gunshots and quickly came under fire. Several bullets hit the patrol car's windshield but the officer was unharmed.

Soon more units, including a SWAT team, arrived on the scene, in an area of west Houston just east of the Sam Houston Tollway, a major highway dissecting the Texas city.