Updated

The Texas man who is suspected of shooting and killing himself and another doctor inside an Austin medical office on Tuesday was a pediatrician who had just been diagnosed with terminal cancer and had recently applied for a volunteer position at the firm, police said Wednesday.

Bharat Narumanchi, 43, went to Children’s Medical Group on West 35th Street just before 4:30 p.m. Tuesday, when he "displayed a gun immediately," the Austin Police Department (APD) said.

Five people were inside the office at taken hostage at the time, police said, though no patients or children were present. Narumanchi "told the hostages to tie themselves up," Austin Police Lt. Jeff Greenwalt told reporters during a news conference Wednesday.

Four of the hostages, all of whom were employees, were able to get out, either by escaping or after Narumanchi released them before authorities arrived, police said in a news release.

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Dr. Katherine Lindley Dodson was "not able to escape" and was then the only remaining hostage, Greenwalt said.

Dr. Katherine Lindley Dodson was killed Tuesday when another doctor took her and four others hostage in an Austin, Texas children’s medical office, authorities said. (Ascension Seton)

When SWAT units arrived at the scene, they "were not able to make contact with anybody inside, were not able to establish communication and we're not able to hear anything as far as a disturbance or calls for help or gunshots," Greenwalt said. "Several hours later, when SWAT was able to get eyes inside of the business to see what was going on, we were able to see that both subjects were deceased."

It’s unclear what led to the deaths or who was inside the building, though a negotiator speaking into a loudspeaker had said: "I want to help you work through this. You have saved a lot of lives."

Austin police eventually sent in a robot, which identified a victim before a SWAT team decided to go inside.

Police believe Narumanchi fatally shot Dodson, also 43, before turning the gun on himself.

Investigators are still working to learn more about Narumanchi’s link to the doctor’s office but said he had applied -- and was turned down -- for a volunteer position at the firm just a week earlier.

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He reportedly encountered Dodson and other doctors during the previous visit, though police do not yet know why he targeted Dodson.

Police also said Narumanchi had recently been diagnosed with terminal cancer and "was only given weeks to live," Greenwalt said.

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"We feel like his terminal cancer probably played a large part in whatever it was that occurred in his life and what was happening yesterday," Greenwalt said. "We don't know exactly why he chose to take these actions or target this particular business. So we're asking if anybody is as friends with either Dr. Dodson or Dr. Narumanchi, knows why he may have wanted to come to this particular business or knows what may have been going on in his life … Please call out to the Austin Police Department tip line."

On Wednesday, an answering service employee working for Children's Medical Group told Fox News the office is not accepting any phone calls or messages. 

Police said they received a call at 4:29 p.m. Tuesday for a report of a man that entered the business with a gun and was holding people hostage. Officers responded to find someone barricaded inside the office, prompting them to call in the SWAT team.

In addition to the pistol, police said Narumanchi had brought with him two duffel bags and an apparent shotgun.

The hostage situation lasted roughly six hours, local affiliate FOX 7 Austin reported.

"When I arrived on the scene, I saw a woman being escorted by police out of the taped area where she was met and hugged by a child," FOX 7 Austin's Amanda Ruiz reported late Tuesday. "And that's what we've been seeing over the past few hours: multiple people being walked out and handed off to what we can only assume are loved ones."

Greenwalt told reporters on Wednesday they were able to get in touch with the suspect’s family "even before we discovered everybody deceased inside the business."

"They're absolutely cooperating with the investigation. I think yesterday's events surprise them as much as it did us," Greenwalt said. "They had expressed interest in wanting to reach out to the victim's family, too. This is a shock to them as it is to the rest of us program."

Dodson, a pediatrician, was beloved by patients and their families, several people told the Austin American-Statesman.

"You saw her at your worst when your kid was sick, and she just always had a smile on her face," said Karen Vladeck, whose two children were among Dodson's patients. "She made you feel like you were the only parent there, even though there was a line of kids waiting."

Police are asking anyone with information or video related to the incident to call APD Homicide at 512-974-TIPS or email homicide.apd@austintexas.gov.

The Associated Press contributed to this report.