Chicago (CNN) The father of a Chicago teenager who was among six people hit by gunfire said Wednesday he will put aside grieving until he gets answers as to why his son was covered in a sheet for an extended period when he was still alive.

Eric Carey's son, Erin, died later at a hospital. Officials said paramedics treating him at the scene thought he was dead or mortally wounded.

Bystanders at the scene of the shooting alerted first responders that the 17-year-old recent high school graduate appeared to be breathing and moving. Erin Carey died hours later.

His father told reporters that first responders dropped the ball on treating his son. He thinks his son, who was shot in the head multiple times, waited almost an hour as paramedics treated other people.

According to CNN affiliate WLS , one other person was killed and four people were wounded outside a party in the Near West Side. A WLS camera was at the scene for at least 15 minutes before paramedics took the sheet off the teen and tried CPR.

Carey said he watched video of the emergency response that showed the sheet over his son.

"That could not have been proper procedure," Carey said. "When you walk into a room you assess the situation and you respond to what you see. If they (saw) my son laying there with a gunshot wound to his head you don't throw a sheet over his head and walk to the next person."

On Wednesday, Chicago Fire Department spokesman Larry Langford said police officers on the scene notified paramedics that Carey was still alive.

"Obviously something went wrong," Langford said Wednesday afternoon. "This is not acceptable. This is not the standard in which the Chicago Fire Department operates."

Langford said that, while this was a scene with multiple gunshot victims, "the city has the resources to get people out of there."

"Did we declare him dead? We did not," Langford said. "We did not pronounce him dead. We had him in a triage. When you get an ambulance on a scene and we do triage, we have to make decisions. Who can I save and who can I not? ... We're going to transport him."

While acknowledging there may have been other victims at the scene whose injuries would give them placement in the first ambulances to arrive, Langford said it should not have taken the approximately 50 minutes that passed before Carey was on his way to the hospital.

Eric Carey said a doctor should be the one making the determination whether a person can survive his wounds.

He said he would press people for answers to his questions about why his son wasn't treated and taken sooner to a hospital.

"I need everyone to do their job because I am going to do my job as father and find out what happened," he said, adding he also wants to know why his son was shot.

Chicago police spokesman Anthony Guglielmi said Tuesday that detectives were investigating whether Erin Carey may have been involved in the escalation of the shooting incident. A Mac-10 machine pistol was found in the street near Carey's body, he said.

Eric Carey laughed off the suggestion his son would have had a gun.

"What did he need? He didn't need anything." the father said. His son was lovable and respectful, a teen who mentored others and was working a city internship at a home for seniors, he said. The son also didn't want to disappoint his father, Carey said. He never would carry a gun.

"He was not designed like that," Carey said.

He said his priority right now was to see his son buried with decency and respect. Then he wants the people who made errors at the shooting scene to be identified and retrained.

Attorney Nenye E. Uche said the response was shameful and Erin Carey could have been saved.

"I think their conduct was not just negligent, was not just reckless, but definitely disgraceful," he said.

Five people were trying to alert paramedics that Carey was still alive, he said. They were begging the first responders to do their jobs, he added.

Langford said the fire department investigation was looking at radio transmissions, GPS data and statements from emergency responders.

"We have to do extensive interviews, which will take some time. We first need to identify where the issue was," he said.

Langford said the typical ambulance response time is five to eight minutes from the time the call comes in. Ambulances normally leave a scene within 10 minutes if a victim's wounds are as severe as those in this incident. The type of head injury suffered by Carey would be considered a so-called "load and go," according to Langford.

Investigators will also determine who placed the sheet over Carey's body, he said.

Police are also investigating.

Carey was one of nine people killed in Chicago over the June 15 weekend, police said.

At least 56 people were shot, making it the most violent weekend of the year -- one resembling weekends of the previous two years when murder rates soared. At least 650 people were killed in 2017 and 771 people were killed in 2016, the most violent year in Chicago in 20 years.

Before last weekend, the police department had touted a significant drop in gun-related shootings and killings all year. There have been 15 consecutive months of declining gun violence, according to police.

Through the first five months of this year, there were 229 fewer shootings and 52 fewer killings, representing a 21% drop in gun violence, according to police. In the month of May, police recorded a 21% decline in killings compared to 2017.

But last weekend was the hottest of the year in Chicago, testing the city's ability to control violence when much of the population is outdoors. Temperatures reached close to 100 degrees all weekend and Sunday was the hottest Father's Day in Chicago in 20 years, with a heat index that made it feel like 109 degrees in the city.