A CNN correspondent choked up on air describing the bloodstained walls and floors of a bunker where people were shot 'in calculated, cold blood' by Hamas militants

• Nic Robertson was visibly emotional while describing a bloodstained bunker he visited in Israel.
• The bunker was located near the music festival that was attacked by Hamas on Saturday.

CNN correspondent Nic Robertson choked up on air while recounting a harrowing experience visiting a bloodstained bunker in Israel amid the nation's ongoing war with Hamas.

Robertson told CNN's Jake Tapper in an interview that aired on Monday about his visit to a rocket shelter near the music festival that Hamas attacked.

The Palestinian militant group launched a surprise attack on Israel on Saturday, firing thousands of rockets from Gaza. Fighters from Hamas massacred civilians attending the Tribe of Nova Music Festival on the same day. At least 260 bodies have been recovered from the music festival attack.

"The smell when you step into a shelter is kind of what hits you first," Robertson told Tapper, adding that people had sought refuge in these shelters when Hamas attacked.

"And you realize that this stuff on the floor is what you fear it is," Robertson added. "It's blood, and you realize in an instant, looking at the strewn shell casings on the floor, looking at the bullet holes in the concrete in front of you, and you can understand what happened."

"Hamas had gone in there with guns and quite literally shot them in calculated, cold blood as they were cowering there on the floor," Robertson said. "And the blood's on the wall, and the blood's on the ceiling, and the bullet holes are in the concrete wall."

Robertson was not the only one who got emotional on live TV while discussing the attacks.

White House National Security Council spokesperson John Kirby also choked up when he spoke to CNN's Tapper about the grisly images being circulated online.

"Sorry. It's very, excuse me, very difficult to look at these images and the human cost. These are human beings, they're family members, they're friends, they're loved ones, cousins, brothers, sisters," Kirby told Tapper while holding back tears.

Israel declared a state of war on Sunday, with officials saying their goal was to vanquish Hamas and take complete control of Gaza.

Civilian deaths and injuries have been reported on both sides. Israeli authorities said that more than 900 Israelis have been killed. According to the Gaza Ministry of Health, the war has claimed at least 687 lives in Gaza, with thousands more injured.