Two firefighters were injured, and two residents sought medical attention early Thursday morning after a fire ripped through the upper levels of a five-story apartment building in the West Bronx.

More than 50 residents were evacuated from the walk-up apartment building at 1793 Sedgwick Avenue in Morris Heights shortly before 4 a.m. Forty-nine people were transported by bus to a nearby Red Cross reception area for food and shelter.

One firefighter was seriously injured when the third-floor landing of the building’s staircase collapsed.

According to one resident, the fire appeared to have started in the hallway of the third floor, where someone had recently placed an old sofa waiting to be disposed. The cause of the fire is still unknown.

1793 Sedgwick Ave, the site of the fire. Photo: Zach Schonbrun

“Everybody was panicking — nobody knew where the smoke was coming from,” said Carlos Mosleh, who lived on the third floor. “People were screaming, kids were crying.”

A fire department spokesperson said Engine 75 was the first to respond and eventually 12 units and 65 firefighters turned up at the 37-year-old building located adjacent to the New York State Thruway along the western edge of the borough. The fire was brought under control by 4:45 a.m.

Those who witnessed the incident recalled a scene of panic and confusion as residents piled down the stairwell and clambered out fire escapes to evacuate. Others on the lower levels, however, did not even know what happened until later in the morning.

“I walked outside and saw a flooded hallway with black water on the floor,” said Jasmin Hernandez, who lived on the second floor. Hernandez and her four children, ages 7 to 1 year-old, were unaware what was going on above them. The alarms in her apartment did not go off.

“I just heard people running down the stairs and I heard a lot of commotion,” Hernandez said. “But nobody knocked on my door.”

A first-floor resident, Christopher Graves, said he and his family were sound asleep during the ordeal. He opened up his apartment door hours afterward to find a gaping black hole where the stairwell used to be.

“It’s a little berserk in there right now,” Graves said.

The landing on the stairwell between the third and fourth floor was the segment that collapsed under the weight of several fire fighters and residents.  In September 2008, a complaint was filed through the city regarding the condition of the stairwell, but a subsequent inspection revealed no structural defects.

The Department of Buildings has put a partial vacate order on the building, and many residents were still unable to reach their apartments due to the damaged stairwell. A spokesperson for the Red Cross said 16 families have been displaced from their apartments and will receive temporary housing, but there is no indication of when they will be able to return to their homes.

Other residents were concerned about how long it would take the building’s owners to repair the damage, and whether the fire-stricken area would become a target for criminals.

“This is like the worst place in New York,” said the clerk at the Deli Grocery market underneath the apartment building. He was fearful that the blaze has left the block  more vulnerable now to thefts and burglary.

The building sits less than a mile from where the violent anti-gay attacks on three men took place earlier this month.

“There’s always fights, always bums hanging on the stairs,” the store clerk

— Amara Grautski contributed reporting on this article