Now that the vulnerability of the building has been exposed, many are wondering what's next.
Police Chief Doug Kowalski with the Prosper Police Department has experienced a similar attack and has ideas that might benefit Dallas police.
When Kowalski heard of the attack on Dallas police headquarters, the former DPD SWAT commander had one thought.
"It was like Deja vu, yeah," said Kowalski.
On Aug. 17, 2010, 29-year-old Patrick Gray Sharp pulled his truck and trailer into McKinney police headquarters.
He tried to blow up his trailer before hiding in a nearby tree line and firing at police.
"He was firing rounds into the building fired about 163 rounds from that position," said Kowalski.
As McKinney's police chief at the time, Kowalski says by design, the building had bullet- and blast-proof walls and windows.
"It was 9 o'clock on a weekday morning and there was probably close to 100 people inside the building," said Kowalski.
The gunman killed himself and no one else was injured, and Kowalski says that's in part because of those safety measures.
After Saturday's attack, DPD covered its bullet-shattered windows with plywood.
But Kowalski has other ideas for how DPD can even temporarily fortify its headquarters.
"We put plywood up, we put Kevlar behind it," he said. "The Kevlar didn't go to waste because when the bullet-resistant material finally came in to replace the damages ones."
Kowalski says now is the time to harden DPD's headquarters because people have seen it is vulnerable.
"In the final analysis, those are the men and women, both sworn and civilian, that occupy that building that the safety of the public relies on and their safety should be paramount," he said.
Command staff at Dallas police headquarters has been meeting with security experts to find out the best and most practical way to fortify the headquarters building.
They've also been in dialogue with the Dallas police unions.
They plan to meet Friday morning to discuss many of those options, and those union leaders make one thing very clear -- not only do they want to beef up security at the headquarters building; they want all 7 substations fortified as well.