State health officials are investigating clusters of coronavirus cases at Bath Iron Works and among out-of-state residents who attended a wedding in Castine.

Additionally, Maine Department of Corrections officials were awaiting test results on 35 youth detainees and 187 staff members at the Long Creek Youth Development Center in South Portland after a teenager recently released from the facility tested positive for COVID-19, the disease caused by the coronavirus.

The additional investigations were discussed on a day when the Maine Center for Disease Control and Prevention announced 28 new cases of the COVID-19, as well as one additional death. That person, identified only as a woman in her 60s from Kennebec County, raised the total number of deaths among individuals with COVID-19 in Maine to 105.

Earlier Monday, the Maine CDC had released numbers showing 30 new cases but later revised the figure after two cases initially listed as “probable” tested negative. The agency also said 30 more people reported to epidemiologists that they had recovered from the disease on Monday, prompting another midday update.

“Outbreaks move pretty fast,” Dr. Nirav Shah, director of the Maine CDC, said on Twitter while explaining the changes.

At Bath Iron Works, the Maine CDC planned to offer testing to 53 people who were determined to have been potentially exposed to three workers who have tested positive for COVID-19. If necessary, the Maine CDC will offer department-by-department testing at the shipyard, which is one of Maine’s largest employers with more than 6,000 workers.

Shah said the three people who have tested positive carpooled, two worked in the same department and all three participated in union activities. BIW’s largest union, the Local S6 of the Machinists Union, is currently on strike over contract disagreements with management at the General Dynamics-owned shipyard.

In a statement, BIW management encouraged anyone who worked in the same area as the three employees, participated in Local S6 picket lines between June 22 and June 24, or took part in rallies in the main yard of the facility between June 15 and 19 to be tested.

“We are working closely with the Maine CDC and have urged employees to practice COVID-19 safety guidelines with a renewed sense of dedication in light of this new information,” the company said in a statement. “We are especially urging employees to abide by state restrictions on carpooling and to check their temperature daily prior to coming to work and to stay home if they have a fever or any other symptoms of COVID-19.”

The Maine CDC is running tests for more than 200 residents and staff members at Long Creek Youth Development Center, which is Maine’s only youth detention facility.

Commissioner Randall Liberty said roughly 80 percent of residents and employees at Long Creek had been tested as of Monday afternoon but no additional results had come back to the corrections department. The individual who tested positive, identified only as a 16-year-old female, had been held at Long Creek for 21 days before she was tested on the day of her release last Friday.

Liberty said staff were already practicing heightened hygiene because of the coronavirus pandemic but are taking additional steps, including medically monitoring, separating youth housed at Long Creek from each other and use of personal protective equipment.

“So we are doing all the precautions we can do to keep the residents safe until we receive our test (results), which will guide our future actions,” Liberty said.

The Maine CDC is also monitoring a potential outbreak among attendees of a wedding in Castine.

Shah said seven people from outside of Maine subsequently tested positive for COVID-19 after returning to their home states.

“We have touched base with the health department of those states to learn about what they have seen,” Shah said. “We have also been made aware of a single individual who is, himself, an out-of-state resident but spends time in Castine who has also tested positive.”

The number of new COVID-19 cases reported daily has trended upward in recent days, with Maine averaging 35 new cases during the past week compared to an average of 23 per day for the week ending on June 22. Looking back over two weeks, however, Maine’s 14-day average was 29, which is four lower than the figure for the two-week period ending on June 15.

To date, the Maine CDC has reported 3,219 total cases of COVID-19. That figure includes 2,863 cases that were confirmed through molecular tests and 356 “probable” cases in which a person with symptoms either tested positive on an antibody test or had close contacted with a known infected person.

The number of active cases being tracked by the Maine CDC also has ebbed and flowed in recent days. After subtracting the 105 deaths and 2,623 individuals who have recovered from the disease, there were 491 active cases of COVID-19 in Maine as of Monday, which is a decrease of 19 from Sunday.

The number of active cases in Maine fluctuates daily, but the rolling average for the seven-day period ending on Monday was 467, compared to 470 for the week ending on June 22.

The number of COVID-19 cases reported nationwide has jumped significantly in recent weeks, driven largely by record daily tallies in states such as Florida, Texas and Arizona. In some of those states, governors are reimposing restrictions and ordering some businesses, such as bars, to close because of the resurgence.

In Maine, the administration of Gov. Janet Mills has allowed most businesses to reopen, albeit with capacity restrictions as well as hygiene requirements such as face coverings and making hand sanitizer available. But bars are still restricted to only serving outdoors, and testing or quarantine requirements for out-of-state visitors is having an impact on Maine’s economically vital summer tourism season.