All but one building in the West End area has reopened after Dallas police asked the public to avoid the area much of Tuesday due to a gas leak.

It happened around 9 a.m., according to Dallas Fire-Rescue. Crews at that time discovered a 6-8 inch gas main was leaking near 302 N. Market St. 

Four buildings were evacuated, two commercial and two residential, temporarily displacing 270-300 people, DFR said. 

Just before 4 p.m., Dallas Fire-Rescue said the gas has been shut off, and all but one building has been reopened and reoccupied.

The building that has not been reopened is a commercial building at 1701 N. Market St. They are still in the process of ventilating the basement of that building.

The streets immediately surrounding that location (Ross Ave., Market St., Corbin St. and Record St.) are the only streets still shut down.

DART said bus and rail passengers should anticipate delays due to the leak and, as a precaution, service in the West End was suspended. The DART West End rail station that was closed has since reopened.

Atmos determines source of leak

It didn't take long for Atmos Energy to determine the source of the leak. It's an underground line at the corner of Market and Ross.  Equipment was used to dig up the street and sidewalk to get to the leaking pipeline. Repair crews vented the buildings until readings were safe enough for reentry.

CBS News Texas Chopper was over the scene, which showed several first responders as well as what looked like construction workers digging holes in the ground.

Officials haven't said what caused the leak.