Somerville officials announced Friday the town will delay parts of Phase Three of the state's reopening plan until July 20 at the earliest, despite Boston planning to enact the new stage of reopening on Monday.

Mayor Joseph Curtatone said he's still concerned about transmission of COVID-19 in indoor spaces in the state's most densely populated city. Theaters and gyms are among the businesses that will not yet be allowed to reopen, as well as outdoor performance venues and larger gatherings.

In an interview with WGBH News, Curtatone praised the Baker administration's work at ramping up testing at the beginning of the pandemic, but also said the current reopening plan endangers residents by leaving too much up to individual cities and towns.

"I may shut a health club down, but if they can go to another city next door and go to that fitness or health club, you know, what good is it?" Curtatone said. "I just keep my fingers crossed. If what the experts are telling us turns out to be true, we're going to face a resurgence. There's a grave danger we're going to see something as close to, if not worse than, what we saw at the beginning. And none of us want to see that."

Curtatone said he has a problem with what he sees as a lack of state-wide coordination and vagueness in Baker's reopening plan. He said he questions whether priorities are being laid out carefully enough.

"We spilled a lot of blood so far. We've made a lot of sacrifices to save lives. Our economy's been brought to its knees," Curtatone said. "Did we bank all that to rush open, to reopen a casino? Or did we bank all that with the hopes that we can get our kids back to school in September and get those parents back to work and bolster our economy?"

The Everett casino Encore Boston Harbor reopened on Sunday, and Plainridge Park Casino in Plainville reopened last week. MGM Springfield is scheduled to reopen Monday.

Curtatone also criticized the amount of leeway in the Baker administration’s guidance for school reopenings. He said in contrast to stringent local guidelines across the state that will incorporate the common 6 feet of social distance, the state guidance allows for a minimum of 3 feet between student desks, which he called “absurd.” He added that it will be challenging to install and maintain up-to-date air filtration systems in all school buildings in his city.

"The other thing, too, is cities and towns and school districts that are already overcrowded — we [were] overcrowded before this crisis," he said. "So it is a monumental challenge with very little time to get it done."