At least 70 people were killed and more than 130 injured when an airstrike hit a detention center in Yemen on Friday, Doctors Without Borders (MSF) said, as the Saudi-led coalition continued to ramp up its deadly offensive on rebels in the war-torn nation.

Another airstrike early Friday hit a telecommunications building in the strategic port city of Hodeidah, causing a nationwide internet blackout, according to NetBlocks, an organization that tracks network disruptions. At least three children were killed in that attack, Save the Children said. The Norwegian Refugee Council said the internet blackout, which was still ongoing as of Friday evening, would affect aid delivery.

The Iran-back Houthi rebels, who control much of Yemen, blamed the Saudi-led coalition for the strikes. CNN has reached out to the coalition for comment. A coalition led by Saudi Arabia and the United Arab Emirates launched an offensive in 2015 to restore Yemen’s internationally recognized government, after it was ousted by the Houthis. The coalition has intensified its attacks in the wake of a Houthi missile and drone strike in the UAE capital Abu Dhabi earlier this week.

The Houthi-run media outlet Al Masirah showed graphic video of people under rubble in the aftermath of Friday’s detention center strike in the northern Yemeni city of Sa’ada. The Red Cross said it had sent emergency medical supplies to two hospitals that had received a “very high” number of casualties.