NEW YORK CITY - A small residential neighborhood in the heart of Brooklyn has seen a worrisome increase in novel coronavirus cases, Mayor Bill de Blasio said Wednesday.

Sunset Park's 228 positive cases spurred the city to launch a hyperlocal attack on the spread of COVID-19, which will include increased testing and outreach, according to the mayor. 

"This is a wonderful, vibrant community where we're seeing an uptick," de Blasio said. "When we see any kind of trend that's unusual, that's when you double down." 

The 228 positives come from about 3,300 tests conducted over the past two weeks in Sunset Park, which now has about a 7 percent infection rate, well beyond the citywide average of 1 percent. 

City officials remain uncertain what caused the COVID-19 case increase and where exactly they are rooted, as residents might have come from neighboring areas to be tested in Sunset Park, de Blasio warned. 

Of 104 COVID-19 cases in Sunset Park on July 29, 80 completed NYC Test + Trace's intake process and provided 130 contacts, said Test + Trace Corps Chief Equity Officer Annabel Palma.

Some Sunset Park residents that NY1 spoke to seemed discouraged by the news. Others did not seem to be tremendously surprised.

“It makes me want to stay inside again,” said one resident.

“If you look around, not a lot of people are wearing their masks, and not everyone is social distancing. So it’s not great to hear, but I’m not totally surprised,” said another. 

“I think if you look at the initial hotspot in corona, the demographics are very similar, you know. We have people living in crowded conditions. We have a very large number of essential workers who have no choice about going to work, And they put themselves at risk when other people are not masked," said one park-goer.

The city will "saturate" Sunset Park's 38,000 households with door-knocks and phone calls and to urge them to get tested, officials said. 

Two mobile testing sites will arrive in Sunset Park, the first on the corner of 44th Street and Sixth Avenue 10 a.m. to 4 p.m. Wednesday through Friday and all next week, the second at Brooklyn Herald Gospel Center at 809 44th St. this weekend during the same hours. 

"We're going to send a lot of support," de Blasio said. "We are going to be focused when we see even a warning light."