(Adds tornado watch, update on power outages)
By Jon Herskovitz
AUSTIN, Texas, March 29 (Reuters) - Four people were killed and nearly 70,000 customers were without electricity on Wednesday after storms pounded Texas, Oklahoma and Louisiana with tornadoes, torrential rain and hail.
Three storm chasers trying to track tornadoes in the Texas Panhandle region died when two cars they were in slammed into each other near Spur on Tuesday night, police said.
In Oklahoma, a truck driver was killed near El Reno in a roll-over crash likely caused by high winds, police said.
One tornado that snapped power poles and trees was reported in Texas on Wednesday about 85 miles (140 km) northeast of Houston, the National Weather Service said. The service issued a tornado watch for eastern Texas, extending into large parts of Louisiana. It also issued a tornado watch for parts of Oklahoma, Arkansas, Kansas and Missouri.
There were 15 reports of tornadoes from the storms overnight on Tuesday in Texas, with most of the twisters in the Panhandle and western parts of the state, the National Weather Service said. Hail, some as large as baseballs, pounded Texas, Oklahoma and Kansas overnight causing damage to cars.
The system took a heavy toll on utilities in North Texas, where provider Oncor said about 50,000 of its customers in the Dallas-Fort Worth area were without power as of Wednesday afternoon. Also thousands of other customers in Texas, Oklahoma and Louisiana were without power, various utilities reported.
The storms led to nearly 70 flight cancellations at airports in Houston as of 4 p.m. CST (2100 GMT), tracking service FlightAware.com reported.
A number of school closed in North Texas on Wednesday morning due to lack of power, causing delays for students taking an annual achievement test known as STAAR, or the State of Texas Assessments of Academic Readiness.
"Storms throughout Texas yesterday and today? Proof that God doesn't like #STAAR either! #imateacher," Twitter user @kekis26 wrote on the social media site. (Reporting by Jon Herskovitz; Additional reporting by Lisa Maria Garza in Dallas; Editing by Andrea Ricci and James Dalgleish)