CHARLOTTE, N.C. (AP) — Police in North Carolina’s largest city planned to update the public on the investigation into the fatal shootings of four law enforcement officers during an attempt to serve a warrant on a suspect in a residential neighborhood a month ago.

The Charlotte-Mecklenburg Police Department scheduled a Friday evening media briefing about the deadliest shooting against law enforcement officers since 2016, when a sniper killed five officers at a Dallas protest. President Joe Biden traveled to Charlotte and met privately with the families of the officers who died.

Officers from a U.S. Marshals Task Force based in Charlotte were attempting to serve a warrant of felony possession of a firearm to a suspect at a Charlotte home April 29 when they came under fire. Officers shot and killed 39-year-old Terry Clark Hughes Jr., who was wanted in adjoining Lincoln County, during a three-hour standoff.

The officers killed were Sam Poloche and William Elliott of the North Carolina Department of Adult Corrections; Charlotte-Mecklenburg Officer Joshua Eyer; and Deputy U.S. Marshal Thomas Weeks. Four other officers were also injured.

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An AR-15 semi-automatic rifle and a 40-caliber handgun were found at the scene. Charlotte-Mecklenburg Police Chief Johnny Jennings said afterward that more than 100 spent bullets had been recovered, although it wasn’t clear how many were fired by the suspect. At least 12 officers also fired guns.

Police have said two females inside the house, including a minor, were cooperating and had not been charged. The department also said detectives were not looking for additional suspects or persons of interest.

Jennings said the day of the shootings that it was suspected that a second person fired at police, but he backed off that idea the next day and said it was still being checked.