HOUSTON—Rescue officials made a gruesome discovery Tuesday morning.

A Cy-Fair ambulance was returning from a call around 2:30 a.m. when paramedics noticed pipes in the road and a guardrail missing along Windfern in northwest Harris County.

When they stopped to investigate, they saw an F-250 pickup truck flipped upside-down in the White Oak Bayou below.

The paramedics found a dead man in the truck and called for backup.

“When they see something that might be an emergency, their training is to investigate and see whatever action they can take to help,” Mark Kimberley, a public information officer for the Cy-Fair Volunteer Fire Department, said.

Officials said it appeared the man died as the result of the crash, rather than drowning.

Debris from the truck was strewn across the water.

Kimberley said he was unsure what caused the crash, but officials were investigating.