Mexican President Andres Manuel Lopez Obrador on Monday sharply condemned the weekend killing of a Salvadoran woman in Mexican police custody, and vowed to bring the perpetrators to justice.

Lopez Obrador said the woman, identified as 36-year-old Victoria Salazar Arriaza, had been subject to “brutal treatment and murdered” after her detention on Saturday by four police officers in the city of Tulum on Mexico’s Caribbean coast.

“It’s a situation that fills us with sadness, pain and shame,” Lopez Obrador told a regular government news conference.

A video published by news site Noticaribe showed Salazar writhing and crying out as she lay face down on a road with a policewoman kneeling on her back while male officers stood by.