Corpus Christi Mayor Joe McComb said the recent "explosion" of COVID-19 cases in his city could be a result of relaxed social distancing mandates and that he now regrets "letting the guard down."

"The reference to letting the guard down was from about March all the way up through Memorial Day, we were at a 2.5 to 3 percent test positive to tests administered. So we were feeling good about we had everything under control," McComb said Thursday on "The Daily Briefing."

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"But with Memorial Day weekend, we had probably over 100,000 people on the beaches. That meant they went into the grocery stores, restaurants, department stores, everything. High school graduation and college graduation in the area....and I think we just felt like we were doing okay. That’s when the spread really started."

On Thursday, Texas officials reported 9,507 new cases and 173 additional coronavirus deaths. In all, the Lone Star State has more than 361,000 confirmed COVID-19 cases, more than 10,000 hospitalizations and 4,521 deaths.

On Wednesday, Corpus Christi reported 502 new cases, bringing the city's total to 9,607, and 116 deaths.

"It's just an explosion. We’re doing everything we can to reduce it. Obviously, once that is out in the community, it’s difficult. We closed our beaches, closed the bars. We’ve got curfews on our beaches at night, from sunset to sunrise," he explained.  "We're really focusing on trying to get people to wear their masks."

McComb said he was hopeful last week as his city's numbers began declining, but Wednesday's 502 new cases threw him for a loop.

"Yesterday we had an uptick. but through the week last week, we were down in the 200s, down to 100 something," he said. Yesterday — I can’t explain it, we had 500. I don’t know whether that is because of a new batch of test results were dumped on us at one time or a one-day deal."

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Asked whether he plans to reopen schools in the fall despite the ongoing surge in cases, McComb said he has instructed the independent school districts to postpone their in-person instruction option until after Labor Day -- emphasizing that the date is subject to change.

"September 8. So that will be the first day that they can have in-school instruction. They can go online or virtually if they want to," he said, "but in-class instruction has been pushed back."

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"We’re doing everything we can," he added. "I personally have an interest in that. My mother is a school teacher. My wife is a school teacher. I have 13 grandchildren," McCabe said, vowing to "work closely with them."