(Adds passenger quotes, video, GE comment)
DURANGO, Mexico, Aug 1 (Reuters) - Investigators began sifting through wreckage of an Aeromexico passenger jet on Wednesday, the head of the country's civil aviation agency said, searching for clues to what caused it to crash as it took off during stormy weather in northern Mexico.
The Mexico City-bound Embraer 190 passenger jet smashed into scrubland near the runway during takeoff from an airport in northern Durango state on Tuesday. All 103 passengers and crew survived by evacuating the plane before it caught fire.
Nearly everyone on the flight suffered minor injuries, Mexican officials said.
Video purportedly of the crash recorded from a plane window showed a dark sky and fog and the ground still visible moments before a thud and shrieking passengers were heard.
Reuters could not independently verify the video.
"The impact was very strong. We wanted to think it was a lightening strike," said Chicago resident and passenger Lorenzo Nunez. "It was terrible, absolutely terrible." Nunez said he had been visiting family in Durango.
A time-lapse video posted by Webcams of Mexico, filmed during the hour before the crash, showed dark clouds and fog or rain moving in.
Aeromexico said in a Wednesday morning Twitter post that 64 people had been released from hospitals.
Two people were in critical condition, including the pilot and a minor, the state health department said.
Luis Gerardo Fonseca, director of Mexico's civil aviation agency, told broadcaster ADN40 that his team began working at the crash site around 7 a.m. local time (1200 GMT), along with representatives of the U.S. National Transportation Safety Board (NTSB) and U.S. Federal Aviation Administration (FAA).
Representatives of Embraer SA and the maker of the plane's engines, General Electric Co, were also assisting, Fonseca said.
Officials said it was too early to say what caused the crash of flight number 2431.
It can take safety investigators months to piece together the complex chain of events leading to an accident.
Determining the cause of the Durango crash may be made easier by the location of the crash, which should allow easy access to evidence, including the two flight recorders, one for cockpit voice recordings and the other for flight data.
Under international rules, Mexico will lead the investigation with support from Brazil, where the Embraer jet was designed and built, and from the United States, where General Electric Co made the CF34-10E engines. (Additional reporting by David Alire Garcia and Daina Beth Solomon in Mexico City, Tim Hepher in Paris and Tracy Rucinski in Chicago; Writing by Tracy Rucinski; Editing by Jonathan Oatis, Toni Reinhold)