The Israeli air force hit a rocket launching squad in the northern Gaza Strip on Monday, reportedly killing three. The airstrike came in response to rocket fire on southern Israel from Gaza and a mortar attack on an IDF patrol, military sources said.

Palestinian news agency Ma’an reported that eyewitnesses saw dozens of tanks entering the Gaza Strip near Beit Hanoun, while warplanes hovered over the area. There was no Israeli confirmation of tanks entering the Strip. The IDF’s spokesman’s Office said forces were conducting “routine activities” in the area.

Gaza’s Hamas rulers reported in a text message to reporters that one of the men killed was a member of the group’s military wing. The Popular Resistance Committees said in an e-mail that the second man was from its ranks.

A third man died of his injuries later Monday night. His affiliation was not clear.

Hamas’s military branch promised to retaliate.

There were no reports of injuries or damage from any of the seven rockets that landed in open areas in the Shaar Hanegev and Hof Ashkelon regions on Monday morning.

“Unfortunately we have been dealing with this threat for the past 12 years, and I believe that it will continue,” Sha’ar Hanegev regional council head Alon Shuster told Ynet news.