JERUSALEM/CAIRO (Reuters) -Israeli troops raided the compound of Gaza’s Al-Shifa Hospital early on Monday in an operation that Palestinian health authorities said had caused multiple casualties and set off a fierce fire in one of the buildings.

The Israeli military said soldiers conducted a “precise operation” and were fired upon when they entered the compound.

“The troops responded with live fire and hits were identified. Our troops are continuing to operate in the area of the hospital,” it said in a statement.

The operation was based on intelligence information which indicated the hospital was being used by senior Hamas leaders, the military said.

“Suddenly, we started to hear sounds of explosions, several bombings, and soon tanks started to roll, they came from the western road and headed toward Al Shifa, then sounds of gunfire and explosions increased,” Mohammad Ali, 32, a father of two, who lives around one kilometre from the hospital, told Reuters via a chat app.

“We don’t know what is happening, but it looked as if it was a re-invasion of the Gaza City,” he added, saying that the military activities began at around 1:00 a.m. (2300 GMT Sunday)

Gaza’s Hamas-run health ministry said a fire broke out at the entrance of the complex, causing cases of suffocation among displaced women and children in the hospital.

It said communication had been cut off, with people trapped inside the surgery and emergency units of one of the buildings.

“There are casualties, including deaths and injuries, and it’s impossible to rescue anyone due to the intensity of the fire and targeting of anyone approaching the windows,” the ministry said.

The Israeli military issued grainy drone footage of the operation which it said showed troops coming under fire from a number of buildings in the hospital complex.

It said troops had been instructed on the importance of operating cautiously as well as on measures to be taken to avoid harm to patients, civilians, medical staff and medical equipment and said patients were not required to evacuate.

Hamas said in a statement the Israeli military had committed a new crime by directly targeting the hospital buildings without caring about patients, medical staff or displaced people in it.

Israel came under fierce criticism last year when troops first raided the hospital, where they uncovered underground tunnels they said were used as command and control centres by Hamas.

The hospital in Gaza City is one of the few remaining health facilities left in the besieged enclave and the Israeli military has long accused the Islamist movement Hamas of using it as a base for its fighters.

Hamas and hospital officials have denied the accusation and the hospital has been at the centre of accusations of war crimes on both sides, with Palestinians accusing Israel of targeting hospitals and Israel saying the sites were being used to shelter armed fighters.