Boston Mayor Marty Walsh said Friday that the city is ramping up efforts to get crucial information on the coronavirus pandemic to Boston neighborhoods that have been hit hardest by the virus.

Walsh said the city is sending seven “sound trucks” into neighborhoods including Mattapan, Dorchester, Roxbury and East Boston beginning on Saturday.

Those neighborhoods have large populations of nonwhite and immigrant populations, groups that have seen disproportionately high rates of COVID-19 infections, according to preliminary data collected by the city.

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The trucks will broadcast messages in various languages, including Spanish, Vietnamese, Haitian Creole and Cape Verdean Creole, on steps residents should take to prevent infection and avoid infecting others.

Walsh also said that COVID-19 testing for the general public, which began a week ago in Boston, is now available at three sites around the city.

The mayor said the city is launching a website to help residents find those testing sites and schedule appointments for testing.

Walsh also strongly discouraged anyone from attempting to run the Boston Marathon route on Monday, and to instead look forward to the re-scheduled Marathon set to take place in early September.

“You’re not a champion,” Walsh said to anyone considering ignoring that directive. “You’re putting people at risk. … No one’s going to be clapping for you.”

For those looking to help fellow residents, Walsh said the city has launched a new program with the website Nesterly to match prospective volunteers with opportunities to help seniors in need during the pandemic.