Wendell Edwards' 11 News report | Witness describes blast | 11 News at 5 coverage

An explosion at a transformer substation in southwest Houston knocked out power to approximately 17,000 customers.

Most of those customers were businesses in the Greenway Plaza and Upper Kirby area.

By 4 p.m., all but a few hundred customers had power again, and as of Friday morning, all power was restored. CenterPoint said it could take two weeks to get the substation up and running again.

The outage caused major traffic delays in the area because so many stoplights were on the blink. The northbound feeder road was also shut down for a couple of hours.

The blast happened near the Southwest Freeway and Buffalo Speedway just before 1 p.m.

"[They were] re-energizing one of their main transformers at this location, they had an explosion which released a large amount of the oil coolant that’s used inside the transformers," said HFD District Chief Robert Schnider.

Witnesses reported hearing two separate explosions before the fire started burning.

"And that's when everyone started running," said another woman.

"It was pretty big," said witness John Daspit who works at a nearby high-rise. "The fireball was easily the size of a large building."

Crews from CenterPoint Energy, HFD and HAZMAT responded to the scene.

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The blast knocked out power to thousands of Houstonians.

Several people evacuated from the Guadalajara restaurant nearby and the Discount Tire.

"It was horrible you guys," said Angela Singleton. "I was in Discount Tire and the young man was talking to me and all of a sudden we heard this big boom and we saw this orange flame.

"It just went up in the air, and then we heard a second one," Singleton said. "And we saw people running out of the restaurant. "I mean it was horrible."

The Houston Independent School District said three schools were placed under a shelter-in-place order: Lamar High School, West University Elementary and the Rice School. The students were released from school around 3 p.m.

A Houston TranStar spokesman said he understood that power was out from the North Loop at Shepherd all the way into West University.

Remote switching was being done to try to return power to customers.

"We are switching right now to try to bring back as many folks on as possible," CenterPoint spokeswoman Alicia Dixon said. "We are trying to isolate the trouble.

"For most folks, I think we're going to be able to bring them on through out the afternoon, but until we're able to get in there, assess the damage and figure out what happened ... I can't tell you exactly how long it's gonna be till everybody gets brought back on," Dixon asid.