It happened around 1:30am on NASA Parkway near Kirby Boulevard. Authorities tell us a man and a woman in a car lost control going around a curve.
Investigators say their car crashed into a taxi cab carrying five people.
An officer who happened to be in the area immediately called for backup.
"He was nearby when he heard it and it sounded like an explosion. He said these two cars just sounded like it just blew up," Pasadena Police Department Spokesman Vance Mitchell said.
The two people in the car and two others in the taxi were killed.
Authorities tell us the passengers in the taxi cab were visiting from Dallas. They were expected to depart on a cruise from Galveston later today.
So far, investigators have not yet released the names or ages of the victims, but they do say no children were involved.