Breaking story updated at 3 p.m. ET

JERUSALEM—Multiple rockets were launched from Gaza towards Jerusalem and cities in central Israel minutes after an ultimatum from Hamas for Israel to withdraw forces from two flashpoints in Jerusalem went into effect at 6 p.m. The Hamas terrorist organization claimed responsibility for the rocket attacks.

There were no immediate reports of damage or casualties.

The attack virtually shut down the nation’s capital as people took cover at a time when thousands of Israelis were parading through the capital’s downtown marking the return of the city to Jewish sovereignty in 1967.

About an hour after the attack, Jerusalem police said that following national security evaluations, celebrations in the Old City could continue. Earlier, police had canceled the events and said they were clearing the area.

But residents remained shaken by the attacks, by the frantic rush for shelter and the sounds of explosions in the distance. As children played outside in the early evening in Jerusalem, the sharp, undulating wail of the all-too-familiar “Red Alert” siren went off. Mothers grabbed their babies and ran for their lives as at least seven explosive rockets—aimed at civilians, not military targets—fell upon the city. In the Knesset, lawmakers who were in session at the time were evacuated by security forces, sending them to bomb shelters in the compound.

Additional rockets were launched at the southern Israeli cities of Ashkelon and Sderot, and thousands more took shelter as everyday life ground to a halt in the face of the attack.

According security officials, Israel is preparing for continuing rocket fire at the center of the country on Monday night, and is directing planes to avoid a flight path that approaches the Gaza Strip.

Earlier on Monday, the military said it was sending reinforcements to the country’s south after also deploying additional forces to Judea and Samaria.

Hamas had threatened violence unless security forces were withdrawn from the Temple Mount and Jews be removed from the Sheikh Jarrah neighborhood by 6 p.m.

As word of the attack spread through social media, Jews all over the world stopped what they were doing and prayed for their brethren in the Holy Land. has issued a call for people to increase in good deeds, mirroring the response of the Rebbe—Rabbi Menachem M. Schneerson, of righteous memory—at other times when Israel and her citizens were under attack. In the tense days leading up to the 1967 Six-Day War, the Rebbe addressed thousands of children at the Lag BaOmer parade held in Brooklyn, N.Y., his words of encouragement broadcast to the entire Jewish people.

“Your brothers and sister in the Holy Land, the Land of Israel, are currently in a situation where G‑d is protecting them and sending them His blessings, success and salvation in an added measure so that they may emerge—and they will emerge—from their current situation successfully,” the Rebbe assured. “Every time you study … and [perform] another Mitzvah … it brings G‑d’s increased blessing for salvation and success.”

He also quoted the blessing and promise contained in this past week’s Torah portion of Bechukotai “You will dwell securely in the Land.”