(NewsNation) — The Texas Tribune reports that video footage, documents, radio traffic and interviews show a “flawed medical response” to the Uvalde school shooting.

According to the report by the Tribune, co-published with ProPublica and The Washington Post, failure by law enforcement to quickly confront the shooter was a key reason victims did not receive “timely care” due to accessibility issues that left medics highly frustrated while racing against the clock to care for victims. The May 24 shooting in Uvalde, Texas, left 19 children and two teachers dead.

The report details that three victims who had a pulse after leaving the school later died. With two of those victims, hospital treatment was delayed because certain resources were not available. Another student who was shot survived for more than an hour but passed away while being rushed to the hospital.

According to the report, only two ambulances were at the school when police killed the shooter and other ambulances struggled to gain access to the school to help victims. Several parked police vehicles blocked the way for ambulances trying to reach Robb Elementary. Some students were even transported to a hospital in a school bus.

Eric Epley, the executive director of the Southwest Texas Regional Advisory Council, told the Tribune medics faced obstacles in their response to the school shooting.

“These scenes are inherently confusing, challenging, and chaotic,” Epley said in an email to the Tribune, also adding, “We remain steadfast that the decisions by the on-scene medical leadership were sound and appropriate.”

The Uvalde school shooting response is under investigation by the Texas Rangers.