Interstate 35E over the Trinity River was shut down for nearly nine hours Thursday morning after a tractor trailer carrying 89 cows to a ranch in Paris flipped on its side overnight in Dallas.
The driver of the trailer, 20-year-old Marcus Melvin Brownlow, has been detained on suspicion of driving while intoxicated. Officers said Thursday afternoon that alcohol was not a factor, but that another drug is suspected. Investigators will not know for sure until tests results are received.
"The driver is being detained as part of the investigation. We are looking real closely at his level of impairment," said Capt. Mark Howard, Dallas County Sheriff's Department. "Preliminary investigation indicates he should not have been driving that vehicle."
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After the crash, all northbound lanes of I-35E were blocked, including the HOV lanes, until the crash was cleared at about 10 a.m.
Investigators said the crash occurred at about 1:30 a.m. when the tractor trailer flipped over as the driver rounded a curve at Colorado Boulevard. His load of cattle shifted, causing the trailer to flip, officials said. Officers said a strong wind may have helped overturn the tractor trailer.
Several cows were killed in the crash while others, freed from the trailer, panicked and jumped over the HOV wall and to their death. All other cows had to be corralled into makeshift pens on the highway.
In all, 70 cows were rescued from the wreckage while another 19 or so died or were euthanized due to their injuries.
Officers said there were dozens of cows inside the semi after the crash, some dead, that all had to be removed before the trailer could be righted.
The roadway was reopened at about 10 a.m.
Brownlow, who was not injured in the crash, will receive citations for safety violations. Also, investigators said he does not hold the proper license and his truck log was not current.
NBC 5's Ben Russell, Amanda Guerra and Christina Miralla contributed to this report.