Italian authorities have broadened their investigation into care home deaths during the coronavirus outbreak after 190 people were reported to have died at Milan’s largest care home.

Police on Wednesday seized documents connected to Pio Albergo Trivulzio, which has more than 1,000 elderly residents, from the offices of the Lombardy regional authorities amid what has been described as a “massacre”.

On 7 April, the newspaper La Repubblica published a photo of nine bodies in the home’s mortuary on its front page, and another of the chapel filled with coffins. There is no official data on how many residents have died in Trivulzio since the coronavirus outbreak, although the newspaper reported on Thursday that there were more than 190 deaths during March and the first half of April.

Silvio Brusaferro, the chief of the Higher Health Institute, said last Friday that 1,822 people had died across all care homes in Lombardy, but it is unclear how many were killed by Covid-19 as many were never tested.

The manager of Trivulzio is under investigation amid allegations that no safety precautions were adopted and that care home staff were not allowed to wear face masks, at least in the early stage of the outbreak, in case they frightened the residents. About 200 staff have been infected with the virus, according to Rossella Delcuratolo from the Cisl labour union.

Meanwhile, under a regional measure, 17 patients who were being treated for other illnesses at a hospital in Milan were transferred to the care home in March to free up beds in packed wards.

“After these 17 people arrived, the first coronavirus cases emerged,” Delcuratolo said. “They said they were not positive but they couldn’t have known as they were not tested for coronavirus. The [home] has been mixing patients who are sick with those who are well, and this is why people are dying. It’s a massacre that could have been avoided if they had listened – on 11 March I asked for all staff to wear face masks, but it didn’t happen.”

Fernanda, 88, who was a resident in Trivulzio’s wing for Alzheimer’s, Fornari, died in the past few days. She had overcome a fever, but was incredibly weak. She was not tested for the coronavirus.

“My human impulse was to cast blame in any possible way,” her daughter, Giorgia Memo, said. “The virus? The system? The lack of swabs? Sure, the emotional turmoil is there, but I’ll be over that soon enough. I’m now convinced that the coronavirus was an opportunity for my mother to break free,” she said, referring to her mother’s death. “She left with a few other elderly people that night.”

Other relatives of those who have died or who are still in the home have joined forces for a potential class-action case launched by Alessandro Azzoni, whose 76-year-old mother, Marisa, is in Fornari.

“The situation in the home is completely out of control and the people inside are either sick or not yet sick, but they’re not being cared for in the way they need to be,” said Azzoni. “I know this is the case for my mother. We have been overwhelmed by messages from either people who have lost someone or who are anxious for parents. We are very frightened.”

Azzoni claimed that when he called the home to check on his mother, who suffered a fever in March, he was told: “It is hell in here, everyone is sick, what do you want us to do? It’s not a hospital.”

Teresa Fusco is also among the relatives. Her father, Ferdinando, was sent home from Trivulzio in March. The 73-year-old had been in the home for two months while undergoing post-stroke therapy. A few days after returning home, he fell ill and tested positive for coronavirus after being taken to hospital.

“He caught it inside Trivulzio, even though staff said it was impossible,” said Fusco. “He’s a little better now but I feel very angry and frustrated.”

Some 600 other care homes across Italy are under investigation.

“Trivulzio is not the only case, but we are waiting for the investigators’ conclusions,” said Pierpaolo Sileri, the deputy health minister.