HOUSTON – A man who was critically injured in a murder-attempted suicide in downtown Houston has died.

Witnesses working on a nearby METRO rail told police they saw the man, Marcos Hinojosa, arguing with Maricela Banda, 33, around 2 a.m. inside a car in the 1800 block of Rusk. They heard gunshots soon after, police said.

A security guard at the George R. Brown Convention Center said she saw the couple arguing. When the woman turned toward her the man "went crazy" and pulled out a gun, the witness said. The security guard ran away.

WATCH: Investigators detail an attempted murder-suicide in downtown Houston

No one else was inside the car, police said.

The woman, believed to be in her 20s, was killed. The man was taken to Ben Taub Hospital in critical condition, but died days later.

Police are investigating the nature of the victim's relationship and what led to the shooting.

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