TULSA COUNTY, Oklahoma - There were several accidents Tuesday morning blamed on black ice, especially before daybreak.

EMSA reported an ambulance was called to 20 car accidents and seven falls on the ice; and there's a good chance of more ice forming overnight.

A section of Highway 169 was one of the more significant trouble spots Tuesday morning. Even though ODOT's plows went through there was enough ice left on the road to cause several accidents.

One of the most serious wrecks involved an SUV that slid into a wrecker waiting to pick up another car.

The accident didn't leave anyone injured, but did draw attention to a slippery patch on 169 just south of 106th Street North.

Six hours after the accident, the section of highway was still icy and slushy while the ramp northbound was covered with ice.

That's despite more than 24 hours of continuous plowing by ODOT's contractor, sometimes traveling in caravans of three plows in a row.

“It takes time. It takes many, many, passes and a lot of material,” said Marty Stewart with ODOT.

Stewart said the snow that melted Monday froze solid overnight and ODOT just wasn't able to clear it before the morning commute.

“As it's warming up, we've gotten a lot of slush, mush, and we can move that around. Ice is just a completely different battle,” he said.

On most of 169 the lanes were clear where ODOT concentrated its efforts and where traffic also helped push the water out of the way.

Further north, there was more ice on the side where ODOT had plowed snow to the side.

It got worse north of Owasso where traffic was lighter.

“It was kind of bad. I could see some black ice sheets in the road, but it wasn't too terribly bad,” one driver said.

While there were several cars left abandoned on the icy sides of the road, most people who went slowly were able to make it just fine.

“I had to drive really slow. It's pretty bad, pretty bad,” another driver said.

ODOT encouraged people to slow down and watch for ice, which they expect to see again Tuesday night.

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They'll have their salt and sand trucks out all night trying to get it off the road.

ODOT has 41 trucks working in Tulsa County - that's just state roads - the county and cities in the county had their own.

ODOT plans to stay at it all night.