What to Know Oncor customers can report outages or ask about restoration by calling 888-313-4747.

Online: Oncor Outage StormCenter

Oncor is getting help from Texas, Alabama and Mississippi, and has talked to partners in Georgia, North Carolina, California and Florida.

About 16,000 Oncor customers, most in Dallas County, are still without power in North Texas Wednesday. Power has been restored to more than 330,000 homes and businesses. An Oncor spokeswoman says they expect the vast moajority of power to be restored by tonight, but that could stretch until tomorrow in the hardest hit areas.

"Just right now the kind of restoration that we are having to do, it's the most complex types of outages, because we are having to reconstruct a lot of these distribution equiptment. So instead of just you know showing up and tunring it on immediately, we are having to remove the trees, remove the damaged polls, re-dig holes for the polls, re-put in the polls and then restring the lines," said Kerry Dunn of Oncor.

More than 220,000 customers are still without power in North Texas Monday morning after a severe thunderstorm blew through the region Sunday.

At it's peak, as many as 350,000 customers lost power across the Metroplex Sunday — with Dallas County seeing the most outages, according to Oncor Electric. Oncor had warned the outage was expected to last for several days.

"This storm was really unique because we saw damage akin to something we’d see with a tropical storm or a tornado. But instead of a small area, we’re seeing a very large portion of Dallas County with major damage," said Oncor spokesperson and meteorologist Jen Myers.

Oncor says the efforts to restore power have been impacted by fallen trees, debris and poor driving conditions. In some areas, power lines and distribution equipment have to be rebuilt.

"Most of the damaged infrastructure we have isn’t because wind blew over our infrastructure, it’s because wind blew something into our infrastructure," Myers said. "We’re talking entire trees, large tree limbs. If you’ve driven around Dallas, you know what's out there and what’s on the ground. Before it hit the ground, it hit some our infrastructure."

Crews from 11 states are working around the clock.

"We put out that call for help. The crews came, definitely answered that call, so they were driving through the night," said Kerri Dunn of Oncor.

Some customers may have damage to their meter base and weatherhead, where power lines connect to their homes. In those cases, the customer would have to call an electrician to repair the damage before Oncor can restore power. Some customers may need to contact the city for an inspection.

"We’re not just out of power here but when that tree fell, it decided to take down the power lines from the house," said Scott Robson who lives in the Lochwood area of Dallas.

Robson says an electrician made repairs on his property and now he's waiting for Oncor to restore power to his neighborhood.

"They've got a big big job ahead of them, they have a big task on their hands," he said.

There were power lines down on Biscayne Boulevard in Old Lake Highlands. Power has been out there since Sunday. Linda Riley's car was covered in tree limbs until her son moved them.

"I could not get it out, so I have been without a car since Sunday. I haven’t been able to leave the house and get food or anything so it has just been a horrible experience," said Riley.

Dallas city officials said Monday that residents without power can find temporary relief from the heat, or power their mobile devices, at city libraries and recreation centers. Diane Johnson of Dallas did just that. She charged her cell phone. Johnson lives with her 107 year old mother.

"If something happened to me or my mom, I'm able to at least dial 911," said Johnson.

However, as of 11 a.m. Monday, the Lakewood, Oak Lawn, Preston-Royal, Skillman-Southwestern, Skyline and White Rock Hills libraries are without power. Thankfully, cooler and less humid conditions are expected for the next several days, according to NBC 5's team of Weather Experts.

City spokeswoman Anastasia Reed said that as of early Tuesday morning, about 300 traffic lights were inoperable across Dallas and another 80 were flashing red; motorists are asked to treat flashing signals as they would a four-way stop.

Cleanup crews are still trying to get a handle on everything that was hit. "Our sanitation team has never seen this type of damage in recent years," said Reed.

If you see a downed power line, do not approach it. Keep a safe distance away from the line and immediately call 911. Do not attempt to remove debris or tree limbs from areas near power lines, Oncor warned.

Oncor customers can report outages or ask about restoration by calling 888-313-4747.

Online: Oncor Outage StormCenter

NBC 5's Diana Zoga and the Associated Press contributed to this report.