(CNN) -- Two tractor-trailer trucks crashed and burst into flames Thursday on a bridge between the United States and Mexico, shutting a key border crossing and killing four people, police said.



Police look at the aftermath of a fiery crash on a bridge linking Reynosa, Mexico, and Pharr, Texas.



The collision on the Pharr-Reynosa International Bridge in Texas triggered a chain-reaction accident with three other vehicles, said Lt. Lupe Salinas with the Pharr Police Department.



A pickup flipped off the bridge, killing three people. Another person died in a vehicle that struck one of the tractor-trailers. Six others were injured.



Pharr Emergency Management Coordinator Elsa Sanchez told The Associated Press the pickup truck had Texas license plates, and the two 18-wheelers and a minivan involved in the wreck appeared to have Mexican plates.  Watch aftermath of fiery crash »



The accident happened around 7:30 p.m. (8:30 p.m. ET). The bridge was closed for the rest of the evening.



The bridge reopened on Friday morning after Texas Department of Trnasportation engineers inspected it, according to CNN affiliate KRGV.



The bridge is normally open from 6 a.m. until midnight and is closed overnight.



The 3.2-mile-long bridge connects U.S. 281 in Pharr, Texas, to the city of Reynosa in the Mexican state of Tamaulipas, according to the city of Pharr's Web site. On an average day, the site says, 5,800 vehicles cross it. E-mail to a friend



CNN's Ed Payne and Jessica Jordan contributed to this story.
What reopens on Friday? What started the crash? When did the bridge reopen? Where did the accident happen? What happened to the two tractor trailers? What kind of accident killed four people? What happened to the pickup truck? Where was the bridge?
The bridge tractor-trailer trucks Friday morning Pharr-Reynosa International Bridge tractor-trailer trucks crashed and burst into flames tractor-trailer trucks crashed and burst into flames flipped off the bridge, linking Reynosa, Mexico, and Pharr, Texas.
question: What reopens on Friday?, answer: The bridge | question: What started the crash?, answer: tractor-trailer trucks | question: When did the bridge reopen?, answer: Friday morning | question: Where did the accident happen?, answer: Pharr-Reynosa International Bridge | question: What happened to the two tractor trailers?, answer: tractor-trailer trucks crashed and burst into flames | question: What kind of accident killed four people?, answer: tractor-trailer trucks crashed and burst into flames | question: What happened to the pickup truck?, answer: flipped off the bridge, | question: Where was the bridge?, answer: linking Reynosa, Mexico, and Pharr, Texas.