FRANKFORT, Kentucky — Warning of a growing complacency in fighting the coronavirus, Kentucky’s governor said Monday the state is experiencing a surge in cases that needs to be met with a commitment to public mask wearing.

The Bluegrass State had nearly 5,000 coronavirus cases last week — the most in a single week since the pandemic began, Gov. Andy Beshear said at a news conference. After about seven months of efforts to contain the virus, he warned that some people are becoming casual in responding to the health crisis, which could lead to more cases and ultimately more deaths.

“The virus is here and it waits for us to get casual,” Beshear told reporters.

His warning of a renewed surge of COVID-19 cases came on a day many children returned to school across the state.

In recent weeks, Kentucky has repeatedly set record highs for weekly virus cases. The governor urged people to wear masks in public and follow other health guidelines to contain the virus. With colder weather approaching, more people will be inside, where the virus spreads faster, he said.

“Folks, we’ve been at this long enough to know what we can do to reduce the number of cases,” Beshear said. “We’ve done it several times. We’re having the largest number of cases right now. We’ve got to have urgency.”