Two people remain unaccounted for as crews continue to clear the rubble of Thursday's building explosion in the East Village. 

Sources say 23-year-old Nicholas Figueroa was on a date, paying for a meal at the sushi restaurant in the building where the explosion happened.

His date is in the hospital.

Sources say 26-year-old Mosies Lucón was the worker at the cash register.

Figueroa's family says they remain hopeful Nicholas will be rescued.

"We just really praying, find my brother Nicholas, keep hope alive, oldest out of 4 boys, 4 handsome young men," says brother Neal Figueroa.

"I just hope he’s okay. And I hope I’m praying for the best. I know he’s strong and I know he’ll overcome anything," says cousin Anthony Figueroa.

Crews are trying to reach the basement where the blast is thought to have occurred.

Twenty-two people were injured, including six firefighters. Four people were critically hurt. One person remains hospitalized in good condition.

About 60 firefighters remain on scene in the East Village.

Fire Marshals will continue to investigate as debris is moved, allowing further entry. Mayor Bill de Blasio says that may take several days. 

Meanwhile, multiple scenarios that could have caused the blast are being considered.

The focus of the investigation is the new gas system private contractors were working on installing.

Sources tell NY1 it was discovered last year that someone tampered with the meter in the old system—possibly trying to bypass it to avoid paying for gas.

Sources say investigators want to know whether workers were attempting something similar Thursday.

The general contractor, Dilber Kukic, was charged last month with bribing an undercover investigator posing as a city inspector - but police say that case is not relevant to this investigation.

"He was injured in the blast. He has helped us quite a bit with our investigation right now. He received some burns and he's in one of the hospitals right now," says NYPD Chief of Detectives Robert Boyce.

If you want to do something to help those affected by the collapse, the Mayor's Office says right now you should not try to drop off supplies.

Instead, the Mayor's Fund to Advance New York City is taking money donations.