CNN releases video of Syrian assault on ISIS stronghold: 'They're surrounded'

Bomb flashes and sounds of machine guns echoed through the streets of Eastern Syria as one of the final ISIS strongholds came under the attack of Syria.

"The bombing went along all night long," said CNN's Ben Wedeman, wearing a helmet and body armor.

The government gave ISIS fighters an opportunity to surrender, but that offer is now off the table, host Ana Cabrara said Sunday. "The last ISIS fighters are now surrounded and offer to surrender off the table. Military action to wipe them out has begun."

"As far as the number of ISIS terrorists inside, we simply don't know," Wedeman said. "From the beginning of this battle going back more than a month, we have heard the U.S.-backed Syrian forces making estimates that proved wrong time after time. A month ago they were telling us there were 1,500 civilians and 500 ISIS fighters. It turns out as far as the civilians go, it was about 20 times higher than that number. And certainly, with the fighters, several thousand have already surrendered."

He said that his team has spoken with some, but they say "there were still many civilians and fighters left inside."

"What's interesting is that after about 4:50 a.m. of fairly heavy bombardment and some return fire, now I'm able to stand up again, not sit on the ground, it's gone relatively quiet," Wedeman continued. "I just see one fire burning in the distance, but there are planes overhead. What we've seen in the previous two operations where they were attempting to retake this pocket, the bombing went on all night long and well into the following day. So it's hard to sit and understand what the situation inside that camp is."

Watch the footage of the attack below: