A video taken on a bystander's mobile phone, has captured the moments after a church steeple in the US state of Connecticut collapsed onto its church underneath.

The footage, taken by Judi Cox, shows fire trucks and firefighters working at the site, where exposed timbers can be seen jutting out of what's left of the church roof, into a gaping hole where the structure tipped over onto the building below, crashing through the tiles and joists.

The tall, majestic steeple and clocktower that once punctuated the city's skyline are gone, and escue workers and investigators are sifting through what remains - amid piles of bricks, wood and dust. 

In the video, which was livestreamed on social media, Judi Cox says her coworker watched the collapse of the beloved town landmark as it happened, from her office window in City Hall next door.

Police evacuated the area, and Cox asked viewers to pray that no-one was hurt.

"Please say a prayer for anyone involved with that church, that there was no one in the building, no one sitting on the steps, and that the firemen remain remain safe. And policemen as well. From downtown and City Hall, New London, Judi Cox, signing out.”

The First Congregational Church, in New London, CT, was built in the 1850s.  There were fears that further damage could follow, if the steeple's collapse had weakened the building's architectural integrity.  At the scene, emergency response teams inspected the damage from cranes.

The reason behind the structural collapse remains unknown.  The church was sold to Engaging Heaven Church in 2015, whose Facebook page reported that the one person inside the building at the time managed to escape injury. 

Mayor Michael Passero said the city was extremely fortunate in the way the collapse happened, saying:

"It could have been a much bigger disaster for us,"

The building is expected to be demolished, taking with it over a hundred and fifty years of history, dating back to before the city of New London was formed.