New York City Mayor Bill de Blasio is facing mounting pressure to close the city's school system as the coronavirus spreads.

Since the crisis began, de Blasio and New York Governor Andrew Cuomo have said they will keep schools open at all costs until it is no longer safe in an effort to keep working parents, particularly those in the healthcare sector, in the workforce.

But as the US case count topped 2,200 on Friday and the death toll climbed to 50, with many fearing the worst was yet to come, the United Federation of Teachers pleaded with de Blasio to close schools to keep people safe.

Their fear is not only keeping the children together in large groups, but having them and teachers commute across the city, potentially picking up the virus, then bringing it into their homes and communities where it may affect more vulnerable people.

'We understand the immense disruption this will create for our families.

'But right now, more than a million students and staff crisscross the city every day on their way to schools, putting themselves and others at risk of exposure and increasing the likelihood of bringing exposure into their homes and communities,' UFT President Michael Mulgrew told The New York Post in a statement.

Mulgrew said he appealed to de Blasio himself but that he denied his request.

Mayor Bill de Blasio gives a press conference in New York on Friday on New York's response to coronavirus

There are now more than 2,200 cases of coronavirus in the US and 50 people have died

NYPD officers say they have been given expired and half-empty bottles of hand sanitizer

Earlier this week, he said he was trying to avoid closing schools city-wide because it was a 'slippery slope' to creating chaos in the city.

Many kids' parents are doctors, nurses or healthcare staff who would be unable to find childcare and therefore would be unable to work if he closed the schools.

Additionally, half of the city's children rely on school meals.

Gov. Cuomo also said on Friday that children, even when they get the virus, are not particularly susceptible to it.

Attendance fell from 85 percent on Thursday to 68 percent on Friday across New York City.

One parent told the Post they were not going to wait for public officials to tell them what to do.

'Sometimes you can’t wait for other people to make decisions. You have to make them for yourself,' they said.

Some private schools have decided to close themselves.

Schools in L.A., San Francisco, Chicago and Philadelphia are closed or are due to close next week.

New York City became a ghost town after de Blasio announced a state of emergency on Thursday.

De Blasio denied reports that the NYPD had been denied masks and insisted supplies were abundant

A medical health worker at the New Rochelle drive-thru facility in upstate New York which has the densest concentration of coronavirus in he country

Pedestrians wear protective masks in New York City on Friday while out walking

A person on the subway wearing a surgical mask. De Blasio has urged people to avoid the subway when possible

The Broadway theater district has closed and businesses are only allowed to operate at half their legal capacity. Gatherings of more than 500 people have been banned.

The subway system and buses remain operational and de Blasio firmly told people on Friday that rumors Manhattan was about to be 'quarantined' were untrue after they spread online.

NYPD officers are now patrolling the city with masks but some have complained they are only being given one.

Others say they have been given hand sanitizer that has expired.

The cops had to then top it off with rubbing alcohol.

'We have been fighting to get more safety equipment, but unfortunately for the time being this is what we have to make the best of,' an internal email that was seen by the Post read.

The Police Benevolent Association wrote a letter earlier this week complaining about the supplies its officers were receiving.

'We're all terrified,' a source said.

De Blasio denied their claims about expired sanitizer and a lack of masks.

'We have a request in to the FDA for 2.2 million more N95 masks from the strategic stockpile,” de Blasio said, referring to the CDC-recommended masks.

'We can report right now that [the city Health Department] has 16 million surgical masks in their emergency stockpile and should be getting 25 million more in the next two weeks,' he said.