Harlem buildings.

A deadly gas leak in New York City highlights the danger presented by construction accidents, no matter where they are located. Two apartment buildings collapsed in a largely unexplained blast that is the subject of widespread investigations.

Investigators are still trying to determine what set off the explosion, which detroyed two apartment buildings on Wednesday. At least seven people are known to have died in the blast. Rescue workers fought cold temperatures, gusting wind, and thick smoke as they battled the ensuing blaze.

Although most gas mains and other systems beneath western cities are not as old as in the east, problems still arise due to deteriorating infrastructure.

On construction sites, gas systems can be subjected to stress from being exposed, and having archaic connections opened and sealed for the first time in decades. A growing number of gas explosions are happening throughout Harlem. Since 2008, there have been nine or ten buildings destroyed by faulty gas lines.

Several of these blasts in New York have damaged or destroyed buildings in close proximity. This has traumatized many residents of the area. In 2012, a five-story building in Harlem collapsed, while Syderia Chresfield, executive director of the Harlem Tourism Board, was across the street.

“It’s not something you forget. Whenever I hear loud thumps, it scares me,” she said.

In 2011, a two-story building collapsed onto a bus, injuring two police officers. Juan Ruiz Sr. was killed that same year during the demolition of a warehouse owned by Columbia University. That project was part of new construction at the school.

Two years earlier, 11 people were injured when a concrete wall fell on top of a pizza parlor. At the time of the accident, a construction project was taking place next door to the structure.

Many times, work being done in nearby buildings is not up to city codes, charge local residents. Some groups in Harlem are calling these construction sites “accidents waiting to happen.”