As President Donald Trump insists that schools across America reopen, even as new data shows a startling surge of the coronavirus among children and teenagers, the head of the Centers for Disease Control and Prevention said Thursday that returning students to the classroom shouldn't be done hastily.

"Our guidance is there to help them begin to open, as I said, safely and sensibly.

He said the extent of how severe the coronavirus outbreak will become all depends on how Americans abide by CDC guidelines that advise the use of masks, social distancing and hand washing as well as limiting large gatherings.

Full coverage of the coronavirus outbreak.

"We got to open up," Trump said during a White House briefing.

"We got to open up our schools and open up our businesses.

Gavin Newsom, a Democrat, announced last month that all schools — both public and private — in counties that are on the list for rising coronavirus cases cannot resume face-to-face learning when school restarts, for some districts later this month, and they would have to meet strict criteria before reopening.

A group of parents have since sued Newsom and other officials, demanding that he allow schools to open because their children are "suffering by being deprived" of in-person learning and some are being harmed by a digital divide.

Download the NBC News app for full coverage of the coronavirus outbreak