An Israeli airstrike on Saturday targeted and destroyed a high-rise building in Gaza City that housed offices of The Associated Press, Al Jazeera and other media outlets.

It was not immediately clear if there were casualties in Saturday’s attack. Live Al Jazeera video showed the 11-storey al-Jalaa building, which also houses several residences and other offices, crashing to the ground after being bombed as dust and debris flew into the air.

AP's president said the agency was "shocked and horrified" at the strike.

AP staffers and other tenants safely evacuated the building after the military telephoned a warning that the strike was imminent within an hour. Three heavy missiles struck the 12-story building, collapsing it in a giant cloud of dust.

For 15 years, the AP's top-floor office and roof terrace were a prime location for covering Israel's conflicts with Gaza's Hamas rulers, including wars in 2009 and 2014. The news agency's camera offered 24-hour live shots as militants' rockets arched toward Israel and Israeli airstrikes hammered the city and its surrounding area this week.

A statement from Al Jazeera condemned the attack, calling on “all media and human right institutions to join forces” in denouncing the bombing and to “hold the government of Israel accountable”.

“Al Jazeera condemns in the strongest terms the bombing and destruction of its offices by the Israeli military in Gaza and views this as a clear act to stop journalists from conducting their sacred duty to inform the world and report events on the ground,” the statement read.

“Al Jazeera promises to pursue every available route to hold the Israeli government responsible for its actions.”

A statement from Associated Press President and CEO Gary Pruitt said: "We are shocked and horrified that the Israeli military would target and destroy the building housing AP's bureau and other news organizations in Gaza. They have long known the location of our bureau and knew journalists were there. We received a warning that the building would be hit.

"We are seeking information from the Israeli government and are engaged with the U.S. State Department to try to learn more.

"This is an incredibly disturbing development. We narrowly avoided a terrible loss of life. A dozen AP journalists and freelancers were inside the building and thankfully we were able to evacuate them in time.

"The world will know less about what is happening in Gaza because of what happened today."

The strike comes amid continued conflict between the Israeli military and Hamas.

According to the Israeli military, Hamas has fired some 2,000 rockets toward Israel since Monday. Most of these have been intercepted.

The Associated Press reported that in Gaza at least 139 people have been killed since Monday night, while eight have been killed in Israel.

Since Monday night, Hamas has fired hundreds of rockets into Israel, which has pounded the Gaza Strip with strikes. In Gaza, at least 139 people have been killed, including 39 children and 22 women; in Israel, eight people have been killed, including a man killed by a rocket that hit in Ramat Gan, a suburb of Tel Aviv, on Saturday.

The latest outburst of violence started in Jerusalem and spread across the region over the past week, with Jewish-Arab clashes and rioting in mixed cities of Israel. There were also widespread Palestinian protests Friday in the occupied West Bank, where Israeli forces shot and killed 11 people.

The spiraling violence has raised fears of a new Palestinian "intifada," or uprising, when peace talks have not taken place in years. Palestinians on Saturday were marking Nakba (Catastrophe) Day, when they commemorate the estimated 700,000 people who were expelled from or fled their homes in what was now Israel during the 1948 war surrounding its creation. That raised the possibility of even more unrest.

U.S. diplomat Hady Amr arrived Friday as part of Washington's efforts to de-escalate the conflict, and the U.N. Security Council was set to meet Sunday. But Israel turned down an Egyptian proposal for a one-year truce that Hamas rulers had accepted, an Egyptian official said Friday on condition of anonymity to discuss the negotiations.