Updates at 5:32 p.m. ET

Israel said Tuesday it is expanding its operations against Hamas "and other terrorist organizations" in the Gaza Strip amid an escalation of violence that saw a barrage of rockets fired from the enclave toward Jerusalem, Tel Aviv and other parts of the country.

"No other country lives under such a threat. Israel will not tolerate the firing of rockets on our cities and towns," Prime Minister Benjamin Neyanyahu said on Twitter. "We have therefore significantly expanded our operations against Hamas and the other terrorist organizations in Gaza."

Rockets from Gaza were fired at targets inside Israel. No one was hurt.

Daniel Estrin, who is reporting on the story for our Newscast unit, said the sound of air raid sirens wailed outside his window in Jerusalem. He adds:

"The sirens ended about a minute later, and then — two muffled explosions. Police say a rocket landed in the southern coastal city of Ashdod, near Gaza. There were also air raid sirens in Tel Aviv, and central and southern areas of Israel. Authorities in Jerusalem, Tel Aviv and other cities opened public bomb shelters. Local media said an open-air rock concert in Jerusalem was canceled and thousands of concertgoers were evacuated."

Earlier, Israeli Prime Minister Benjamin Netanyahu said Hamas, which governs Gaza, will "pay a heavy price" for the recent spike in rocket attacks. Israel conducted airstrikes early Tuesday on the Gaza Strip, and the country has called up reservists and is planning ground operations.

"No time limit was put on the operation, but senior diplomatic officials said it could be 'for a long time,' " reports the Jerusalem Post. The newspaper adds that Netanyahu says the time has come to "take off the gloves" to fight Hamas.

The two sides have increased their hostilities since the recent killing of three Israeli teenagers, which sparked a killing of a Palestinian teen in what's being seen as revenge.

From Jerusalem, NPR's Linda Gradstein reports that overnight some 60 rockets were fired from Gaza. Several reached Beersheba and Ashkelon, some 25 miles from Gaza.

Linda reported that Israel called up some 1,500 reservists. An Israeli army spokesman said that in the airstrikes overnight, Israel destroyed the homes of several senior Hamas military men. Palestinian medics reported that at least nine people were wounded, including seven children.

The Israeli Defense Forces has posted video online of two airstrikes from last night, attacks that it says targeted the "activity sites" of two Hamas members involved in conducting rocket fire from Gaza. Helicopters and warplanes took part in dozens of other attacks.

It seems that in at least one case, the activity site was a house — and that the occupants got a phone call telling them to get out before it was bombed.

Reuters reports:

"Witnesses said a house bombed in Khan Younis was flattened. The Palestinian Health Ministry said nine neighbors were wounded by debris from that strike."The Palestinian Interior Ministry said the family in the targeted home had received a telephone call from an Israeli intelligence officer asking them to leave the house because it would be bombed, and the family evacuated in time."Copyright 2016 NPR. To see more, visit http://www.npr.org/.