Israeli forces shelled a hospital in Beit Lahia, in the north of the Gaza Strip, causing extensive damage and destroying medical supplies, the Hamas-run Palestinian health authority said on Thursday.
A spokesman for the Israeli armed forces said the reports were being investigated.
The shelling hit the third floor of the Kamal Adwan Hospital, the authority said.
A military spokesman said some 100 terrorist suspects were arrested in the hospital grounds after some had barricaded themselves inside the facility.
The Israeli spokesman said soldiers found weapons, funds and other material in and near the hospital.
The information from both sides could not initially be independently verified.
The hospital director recently posted on social media that his son was killed in the latest Israeli airstrikes.
Israeli forces have attacked the hospital several times since the conflict began, and on Monday said an operation there had been completed.
The Israel Defence Forces (IDF) have been conducting intensive operations in the northern Gaza Strip, an area they had previously declared cleared of Iranian-backed militants months ago.
But in recent weeks, the army has escalated its air and ground operations to go after militants from the Palestinian militant organisation Hamas who have regrouped into scattered cells.
Dozens of people died in an Israeli attack on a residential building in Beit Lahia on Tuesday.
The conflict began after Hamas and other extremists from the Gaza Strip attacked Israel, killing 1,200 people and abducting up to 250, more than a year ago.
Israel then launched a massive retaliation, which the Gaza authority says has resulted in more than 43,000 deaths.
Israel has come under international criticism given the high number of civilian casualties and dire humanitarian situation in the Gaza Strip.
