NEW YORK (CBSNewYork) — Strong explosions erupted underground near Union Square Friday morning, sending shattered glass raining onto the sidewalk.

As CBS2’s Dave Carlin reported, the rain Friday may have been to blame.

The three manhole explosions and fires happened on Broadway near East 12th Street around 6:30 a.m.

Some compared it to thunder, but stronger.

“There was a big vibration, I felt it on my bed,” said nearby resident Tony Cacaj. “That’s not the alarm clock you want.”

“I really never heard a boom like that before, it was just crazy,” said Jeff Chinman, owner of Broadway Kitchen and Bath.

The subterranean explosions pushed flames up through manholes, with shock waves and debris that shattered the windows of a coffee shop, an apartment above, and a Chinman’s kitchen and bath store.

The most damage was at the Strand Bookstore on Broadway, which was not open at the time of the early morning blasts.

Manhole explosion blows windows out of famed Strand bookstore. No one hurt. #fdny @wcbs880 pic.twitter.com/UTTVqZaqYi — Marla Diamond (@MDiamond8) March 31, 2017

Bookstore managers tweeted some reassurance.

“Hi Strand fam, thanks for checking on us this morning. The Strand (& books) are safe!! We are currently closed, stay tuned for updates.” the store wrote in a tweet.

Hi Strand fam, thanks for checking on us this morning. The Strand (& books) are safe!! We are currently closed, stay tuned for updates. ❤️ — Strand Book Store (@strandbookstore) March 31, 2017

But the bookstore had to close for the day, and a planned discussion on neoliberalism by Borough of Manhattan Community College professor Maureen Matarese had to be called off. The discussion had been planned for 7 p.m.

The FDNY’s Ladder 3 truck was also singed while sitting on top of one of the fires, 1010 WINS’ Al Jones reported.

A trio of manhole explosions shatter windows at Broadway and E12….including Strand bookstore. #1010WINS pic.twitter.com/CDa9JGuRXV — Al Jones (@aljoneswins) March 31, 2017

“We ran out and there was flames under that underneath the fire truck,” Chinman said. “The flames were coming out pretty steady.”

Two firefighters suffered minor injuries and did not require treatment at the scene, according to the FDNY.

The FDNY said high levels of carbon monoxide prompted evacuations of some nearby buildings, CBS2 reported.

“We subsequently searched (the buildings); vented them,” said FDNY Deputy Chief Bob Carroll.

The explosions are likely linked to the rainy weather, according to a Con Edison spokesman. He said it is what you can get when lots of leftover salt from recent snowstorms gets pushed underground.

“Anytime you have some sort of salt into our electrical system, it’s just not good,” said Con Edison spokesman Sidney Alvarez.

The salt can make contact with lines and spark, officials explained.

East 12th Street was closed between Broadway and Fourth Avenue, and two blocks of Broadway were also closed – leaving motorists struck in traffic.

“I have seen the light change seven times – seven times, and we’re still here in the same place,” said driver Miguel Cornelio of Paterson, New Jersey.

Luckily, no one was injured in the blasts and Con Ed said there were no service disruptions for the neighborhood.

The FDNY added that while the danger had passed late Friday afternoon, they would keep a crew on the scene at 12th and Broadway as a precaution.