Originally Published: 02 AUG 22 05:26 ET

By Jarrod Wardwell, CNN

(CNN) -- Two people were killed and six were injured while attending a birthday party at a Detroit home early Sunday after a man upset over a parking dispute allegedly opened fire on the group, police said.

The shooting happened at 2:40 a.m. when a man who lived across the street from the party became upset about his driveway being blocked, the Detroit Police Department said in a Facebook post.

The suspect, who police haven't named, shot from the first and second floors of his home and had "strategically placed" 11 weapons throughout the residence "so as he moved through the home he would have access to these weapons," Detroit Police Chief James White said at a news conference Monday.

"Instead of contacting the police department ... he decided to take matters into his own hands, engaging them and ultimately shooting up the home," White said.

The suspect used a "high-powered rifle," Detroit Police Commander Michael McGinnis said at the news conference.

Most of the eight gunshot victims were in their 30s and one is 19 years old, McGinnis said. One of the injured victims was in critical condition, White noted.

The two people who died, a 39-year-old woman and a 38-year-old man, tried to drive themselves to a hospital but crashed before they could get there, McGinnis said.

Officers "responded in record time," White said, and arrested the suspect, who is in his 30s and has a military background.

The police chief called the mass shooting "a crime that simply did not have to happen," and noted the city tallied seven homicides and 24 non-fatal shootings over the past weekend.

"We understand that these numbers make media headlines, but to us, these represent people," White said. "These represent families, this represents children, this represents husbands, wives, brothers and sisters."

According to the non-profit Gun Violence Archive, the US has had at least 387 mass shootings so far this year.

Both the Gun Violence Archive and CNN define a mass shooting as one in which at least four people are shot, excluding the shooter.