An underground explosion blew the covers off of two manholes in Midtown Manhattan Wednesday morning, sending people into a panic and bringing traffic to a halt for nearly two hours.

The explosion occurred at 8th Avenue and West 35th Street around 10:15 a.m. According to WABC-TV, one of the manholes belonged to Verizon while the other is a Cablevision service box.

Officials say that the smoke was seen coming out of the manholes before the explosion sent the covers flying into the air.

"An electrical burnout caused by wires lead to a manhole explosion," said a Con Edison worker at the scene, according to the New York Post.

Authorities were still investigating the scene by 11:30 a.m. and the street was closed off from traffic.

Witnesses say they heard the two loud explosions, which caused nearby buildings to shake.

"People were running," Steve Czarnacki told WABC-TV. "When the second manhole exploded there was a man just about to walk there, and when it exploded he ran back in the other direction and people started running everywhere."

Another witness added that "The whole building shook, and at first we didn't know if it was the air conditioning turning on or something, but it was a little more extreme, apparently."

Thomas Mcdonough told CBS2 that the explosion was startling.

"I heard a loud explosion, and I felt all this hot air hit me," he said. "And it knocked me back, and I almost went down. I saw the flames flying in the air. I then panic, and I started to go out across the street. And I was waiting a minute and I was going to go on the other side, and the other one went up, and that one really hit me in the face, and the flames went up"

Witness Elle Kitchings also described the chaotic scene that occurred following the blasts.

"People were running, trying to get out of the area because they didn't actually know what it was, and then we realized that it was a manhole cover. The second manhole cover was so powerful it split the manhole in half," she said.

There were also several other manhole fires at 38th Street and 8th Avenue. Fortunately, firefighters quickly put out the blazes, and there were no reported injuries.