"No sense" to ex-con's shooting spree in Mich.

Investigators are trying to determine what led a Grand Rapids man to go on a deadly shooting spree yesterday - and to then take his own life after a tense standoff with police.

Rodrick Shonte Dantzler, a 34-year-old ex-convict, killed seven people, including two children, before killing himself inside a house where he had been holding hostages.

"We heard a gunshot and it turned out to be a self-inflicted gunshot wound to the head," said Police Chief Kevin Belk.

Dantzler is suspected of shooting seven people to death earlier in the day in two separate locations, reports CBS News national correspondent Dean Reynolds.

Three adults and a child were gunned down in one home. In the other, two women - one of whom is believed to have been a former girlfriend of Dantzler's - and his ex's 10-year-old daughter were fatally shot.

Authorities don't have a motive for Dantzler, but say his daughter and an ex-girlfriend were among the seven people killed.

CBS Affiliate WWMT reports that Dantzler had gotten into a fight with his current girlfriend earlier Thursday and told a friend that he would "kill them all."

Mich. man kills daughter, 6 others, then himself

The names of the dead were not immediately released. Autopsies were scheduled for Friday.

Records show that Dantzler was released from state prison in 2005, after serving time for assault less than murder. A spokesman for the prison system said Dantzler had not been under state supervision since then.

Police initially got a 911 call early Thursday afternoon from someone saying that a man had admitted to killing three people, Belk said. Police went to Dantzler's home, but he wasn't there and officers couldn't find him.

It wasn't long before authorities got a call from a woman who said her relatives had been shot.

Next came a call about someone finding four gunshot victims at another house.

Officers soon found three bodies in a home on Plainfield Avenue. An hour later, they discovered the other four across town in a ranch-style house on a cul-de-sac called Brynell Court.

Two of the dead were children.

While police were investigating the seven homicides, Belk said police received a report of a "road rage" shooting.

Dantzler had apparently shot at a man through the rear window of the vehicle he was driving. Police spotted him, and began a chase that included Dantzler crashing into a patrol car in the city's downtown and exchanging gunfire with officers, during which a female bystander was shot in the shoulder.

Danztler drove a sport utility vehicle north from downtown and onto Interstate 96, crossing a grassy median and heading the wrong way down the highway while more than a dozen squad cars pursued him. Belk said he crashed the vehicle while driving down an embankment into a wooded area of the highway, which remained closed hours later.

"I look in my rearview mirror and see this big white SUV coming up behind me," said Carrie Colacchio, who lives a little more than a mile away from where Dantzler later took his three hostages. "The only way to get out of it was to push the gas pedal."

Colacchio said she couldn't turn off the road or slow down or go any other way, and she reached about 85 mph.

"I almost got smacked," she said. "I had to go up on the curb."

From the highway, Dantzler made his way toward a nearby single-family home, firing several shots as he forced his way inside and took hostages he did not know, police said. Dozens of officers with guns drawn cordoned off the neighborhood, near a small lake in the northern part of the city, as authorities shut down nearby Interstate 96.

That was around 7:30 p.m. During the next five hours, Dantzler fired sporadically at officers and inside the house. He vacillated between threatening to shoot the hostages and pleading with police to take him out, even asking negotiators whether there were snipers outside the home and where he should stand, Belk said.

"The suspect fired at our officers many times throughout the night," he said. "Even in the home, there was an exchange of gunfire. He fired as they made entry to the house."

Dantzler had been talking to police at the final location, and he'd also sent out a hostage for cigarettes and Gatorade. The conversation was apparently about surrendering but then for reasons known only to him, he turned the gun on himself.

"Obviously, we're extremely disappointed at the outcome," Belk said. "We would much rather have had the suspect surrender and have him in custody.

"It makes no sense to try to rationalize it, what the motives were. You just cannot come up with a logical reason why someone takes seven peoples' lives."