Dallas police say they're treating a suspicious item found outside police headquarters Monday morning as a hoax bomb. [[320869381,R]]

Officials said the item was a bottle containing a liquid later determined to be water. A note was attached, though police refused to disclose what it said.

Assistant Police Chief Randy Blankenbaker said the note was attached in a way that "caused even further suspicion."

The bottle was found at the north entrance of the Jack Evans Police Headquarters building in the 1400 block of South Lamar Street at about 9:30 a.m.

The Dallas Police Department headquarters are on lockdown due to a suspicious package, according to authorities.

SWAT and Hazmat teams were called to inspect the bottle. The package was determined to be harmless just before noon, according to officials. Police lifted the lockdown shortly afterward.

During the lockdown police said all personnel were asked to move to a safer part of the building. Lamar and Belleview streets were closed down near the station during an investigation.

Police have not released any details about who left the bottle or released the names of any possible suspects.

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The incident comes nearly a month before the anniversary of the July 7 ambush that killed five Dallas officers and comes about two years after police say a man opened fire on police headquarters and left pipe bombs outside before he led officers on a pursuit and was killed.

"Obviously over the last couple of years with what's happened it's become more and more important to officers that they be vigilant about their own safety," Blankenbaker said.

The department has made security upgrades since the incident two years ago and tells NBC 5 that it is still working with security vendors to enhance officers' safety in the city.

NBC 5 law enforcement expert Don Peritz explains the inner workings of the Dallas Police Department as officials react to a suspicious package being found outside the department's headquarters.