AUSTIN, Texas - Police say a gunman fired more than 100 rounds at the Mexican Consulate, Austin police headquarters and other downtown buildings before he was killed.

At a press conference Police Chief Art Acevedo said a police sergeant shot at the gunman, who was about 50, early Friday outside the police station. Acevedo says it's not clear if police fatally shot the suspect or if he took his own life.

The sergeant, who had just completed a mounted horse patrol, was holding the reins to two horses when he fired.

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The gunfire was reported at 2:22 a.m. Friday, Assistant Police Chief Raul Munguia said earlier today.

Acevedo said officers who approached the suspect saw cylinders in his nearby vehicle and discovered he was wearing a vest they thought may be rigged to explode. Officers retreated and a bomb squad was called.

It was later determined the items were not explosive.

The suspect's name was not immediately released.

CBS Affiliate KEYE reports officers were also searching the suspect's Austin-area residence for possible explosives.

Police say no officers were hurt.

Officers then saw what appeared to be an improvised explosive device in his vehicle, and that "the suspect was wearing some type of vest," Munguia said. He did not provide additional details on the garment.

Police are trying to determine a motive for the gunfire.

The shooting incident was declared over by police by 6 a.m. Eastern, but a section of the primary highway through Austin, I-35, remained closed until about 7:30 a.m., when police confirmed it had reopened in both directions.

CBS News correspondent Bob Orr said there was no information early Friday morning to suggest the incident in Austin was in any way connected to protests seen in many U.S. cities this week -- including a demonstration in Austin -- over the decision by a grand jury in Ferguson, Missouri, not to indict a white police officer in the shooting death of unarmed black teenager Michael Brown.

Orr said it would be one of the many possibilities police in Austin looked at as they investigated the deceased suspect.