The Israeli military said Friday it had begun airstrikes in the Gaza Strip in response to a rocket attack on Tel Aviv — which was the first time the city, some 50 miles north of Gaza, was targeted by rocket fire since a 2014 war against Gaza militants. In a statement early Friday, the army said it was targeting "terror sites." It provided no further details.

The attacks were taking place in the southern Gaza town of Khan Younis, about 15 miles south of Gaza City. The warplanes could be heard flying overhead in Gaza City, where smoke from the explosions could be seen about 15 miles away from some of the strikes.

Palestinian media said a Hamas naval base had been targeted. Israeli warplanes could be heard roaring through the skies above Gaza City.

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There were no immediate reports of injuries.

Smoke and flame are seen during an Israeli airstrike in Gaza on Fri., March 15, 2019. Reuters

Minutes later, the Israeli military reported air raid sirens in southern Israel. It said it had identified a launch attempt out of Gaza, but the rocket misfired and landed inside Palestinian territory.

Earlier, in Tel Aviv, air raid sirens were heard wailing after rockets were launched from Gaza. "No interceptions were made by aerial defense systems. No damage or injuries were reported," military officials said.

CBS News has confirmed Israeli Prime Minister Benjamin Netanyahu, who is also Israel's defense minister, is holding an urgent security meeting with his military chief and other senior advisers in wake of the rocket launches.

In Gaza, there was no immediate claim of responsibility.

Gaza is controlled by Hamas, an Islamic militant group that seeks Israel's destruction. The territory is home to other militant groups, including Islamic Jihad, an Iranian-backed armed organization that also has a formidable rocket arsenal.

"The Hamas organization is the main organization in the Strip," chief military spokesman Brigadier-General Ronen Manelis told Israel Radio, according to the Reuters news agency. "It is responsible for what happens within the Strip and what emanates from it."

A post on social media apparently showed two rockets streaking through the night sky above Tel Aviv.

Rocket alert sirens triggered in Tel Aviv and in surrounding central towns pic.twitter.com/s8BWxImwW6 — Daniel Meron (@AmbMeron) March 14, 2019

Tel Aviv Mayor Ron Huldai said he had ordered the city to open public air raid shelters as a protective measure. But he said there were no special instructions and encouraged residents to stick to their daily routines.

"Continue life as usual," he told Channel 10 TV. "Be calm, but be alert."

In an unusual step that indicated Hamas was attempting to prevent further escalation, the Hamas Interior Ministry said the rocket fire went "against the national consensus" and promised to take action against the perpetrators.

Earlier this week, Israel struck Hamas targets in Gaza in response to rocket fire on southern Israel, near the border. Late Thursday, local media said that Egyptian mediators left the territory.

In addition to Hamas, Gaza is home to other militant groups. They include Salafists inspired by the Islamic State group, as well as Islamic Jihad, an Iranian-backed armed organization that also possesses a formidable rocket arsenal. The Islamic Jihad also denied involvement in Thursday's attack.

Earlier this week, Netanyahu issued a warning to Hamas, rejecting suggestions that Israel would be reluctant to take tough action in Gaza ahead of national elections next month.

"I suggest to Hamas, don't count on it," he told his Cabinet. "We will do anything necessary to restore security and quiet to the area adjacent to the Gaza Strip and to the south in general."