ST. LOUIS – The search for suspects and answers continue in last weekend’s mass shooting at a youth party inside a downtown St. Louis office building.

Investigators believe someone used a keycard to get inside and then propped a door open, allowing dozens of teens to come inside.

On Wednesday, St. Louis police pleaded with the public to help find the suspects.

Makao Moore, 17, died in the shooting. Ten other victims, ages 15 to 19, were also wounded or injured.

The shooting occurred around 1 a.m. on June 19, on the fifth floor of a building near the intersection of Washington Avenue and 14th Street.

Police said the teens at the at party could face trespassing charges. Meanwhile, the 17-year-old who was arrested after the shootings was released. 

St. Louis Building Commissioner Frank Oswald said his office is still trying to figure out who hosted the party and exactly how the teens gained access.

“There is a key card that does allow people in and out of the building. That is supposed to be closed on the weekends,” Oswald said. “Somehow, someone got a card to get the front door opened. They propped the door open to allow these people in.”

Detectives are trying to identify heavily-armed individuals seen on surveillance video.

Sgt. Charles Wall, a spokesman for the St. Louis Metropolitan Police Department, said people who attended the party should come forward and speak with them.

“Those are individuals that, as you can tell, some of the individuals appear to be holding firearms. Other individuals pictured, (it) may not be clear as to whether or not they’re in possession of firearms,” he said.

“But they appear to be at the very least communicating with and in close proximity with the individuals that are armed. So, it’s our belief at this time, that those individuals all know each other and all may be responsible for (or) certainly have more information as it relates to this incident.”

Detectives were told 70 or so high school-aged kids were at the party at one point. Sgt. Wall reiterated a sentiment among city leaders and police that downtown is not a place to drop off children unattended.