DALLAS (CBSDFW.COM/AP) — A man walked into a downtown Dallas police substation parking lot with a sledgehammer, broke windows and windshields, and caused thousands of dollars in damage to a dozen police cars, police officials said.

Gregory Simpson, 58, of Dallas, was arrested early Sunday and charged with criminal mischief causing damage of more than $2,500 and less than $30,000.

greg Sledgehammered Dallas Police Cars Raise Concerns For Officer Safety

Gregory Simpson (Dallas PD)

But police union officials said Monday that the sledgehammer incident was just the latest since city officials promised to upgrade security at police department facilities after a 2015 shooting attack outside the department’s headquarters.

Details of the incident Sunday were not immediately available. An arrest affidavit had not been posted to online court records as of Monday afternoon, and a call to an attorney representing Simpson was not immediately returned.

Representatives of the city’s largest police union, the Dallas Police Association, posted pictures to Twitter of some of the damage— concave sledgehammer imprints on windshields, windows and cars. They also posted a picture of three orange cones blocking an entrance to the garage next to a sign saying only police personnel were allowed.

Association President Michael Mata said union officials have been asking for security upgrades to be prioritized for months.

“The mayor and council members got in front of microphones and cameras and said that protecting officers was their number one concern. Very little if anything has been done, now here we are,” Mata said.

In June 2015, James Boulware fired multiple shots at the Dallas Police Headquarters, squad cars and officers from an armored van before leading police on a chase and engaging in a standoff that ended when a police sniper shot and killed him. He had said he was upset about losing custody of his son after an arrest.

City officials said in the following days that they planned to upgrade security measures at headquarters and the seven substations.

Renewed calls for security upgrades were issued after the July 7, 2016, sniper attack on officers who were working at a rally against police violence. Four Dallas officers and one transit officer were killed and nine other officers were wounded during the attack and ensuing standoff.

The city has allocated $3.4 million to enhance lobby security at those facilities including ballistic protections and more control to access. The work started in October 2017 and is expected to finish in May 2018, said city spokeswoman Monica Cordova. Work at half of those facilities has been completed, she said.

“The City of Dallas is committed to providing a safe work environment for our police officers,” Cordova wrote in an emailed statement.

She said a bond package approved by voters last year will allot more than $6.7 million for additional security improvements including parking lot security, fences, bollards and access gates. The projects are scheduled to begin this spring but are spread over several years.

Mata said since the 2015 incident there have been at least four other incidents at substations, including a suspect shooting a substation from a moving vehicle, a man driving into the parking lot of another with several guns, a man who set himself on fire outside of a station and the sledgehammer incident Sunday.

“I know in the bond package they have funds allocated for security measures and I believe they want to do this over a period of years,” he said. “The city keeps rolling the dice and hoping that nothing bad happens. But if this lack of security isn’t fixed, it’s going to turn into a deadly force confrontation. There are going to be citizens or officers injured or killed.”

DPD Security Upgrades:

JACK EVANS

    Percent Complete: 60%

    Estimated Completion: May 2018

SOUTH CENTRAL

    Percent Complete: 80%

    Estimated Completion: March2018

CENTRAL

    Percent Complete: 100% 

SOUTHWEST

    Percent Complete: 100% 

SOUTHEAST

    Estimated start date February 2018 and completion March 2018

NORTHWEST

    Percent Completed: 100%

NORTHEAST

    Percent Complete: 100%

NORTH CENTRAL

     Percent Complete: 90%

     Estimated Completion: February 2018

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)