Al Roker suffered a setback after being treated for blood clots. The "Today" weather forecaster is now back in the hospital.

"He’s resting and his doctors are keeping a close eye on him. Al and his family want everyone to know how grateful they are for all the love, the support and the well wishes," said Hoda Kotb, host of NBC's "Today."

Roker noted on Instagram last week that some of the blood clots traveled to his lungs.

"After some medical whack-a-mole, I am so fortunate to be getting terrific medical care and on the way to recovery," Roker said.

Roker was noticeably absent from the Rockefeller Center tree lighting Wednesday night. It's an event he usually helps host.

Roker also missed the Macy's Thanksgiving Day Parade. He posted on Instagram that he had just been released from the hospital and watched the parade from home.

Roker has been a weather forecaster on "Today" since 1996.

Warning: The above video has footage that may be upsetting to some viewers.

Sept. 11, 2001, was a sunny day in New York City.

Randal Robinson, of Savannah, Georgia, had just arrived for a morning U.S. Customs Service seminar, being held on the fourth floor of Six World Trade Center.

One of the buildings that would soon be gone.

"And then when the thing hit...Boom. One of the New Yorkers said, 'Oh we don't have earthquakes in New York very often.'

And then.... Boom boom rumble rumble.... Dragging scraping sound.

Oh... somebody's moving furniture.

And we thought.... 'Naah.'

Then somebody stuck their head in the door and shouted, 'Everybody out....now! Do not go down the elevator. Come down the steps and follow me.'"

Robinson remembers it all like it was yesterday. How they all dashed down the stairs to the street below. He looked up and saw the smoke.

Somebody said a corporate jet must have struck the building. He couldn't figure out how the pilot could have done it.

"Well heck, it had to be a heart attack or a stroke," he said. "It was beautiful weather. You couldn't miss seeing it. So I said, 'Well, hopefully, they'll get the fire put out soon.' So I pulled out my camera and started taking the pictures."

He snapped about a dozen images before realizing just what he was witnessing.

"So then when I ran out of film," he said, "I put in another roll of film and started to take more pictures and then someone said, 'Oh my gosh, people are jumping out.' So I said no more pictures."

He thought the firefighters would put it out. But they had no chance.

"In a few minutes, someone said 'Oh my god, here comes another one.' This other jetliner was coming down the river. Banked hard left. Came over our heads, engines screaming and hit Two World Trade Center."

He finally made it back to his hotel room and watched on TV with the other guests as the towers fell, including the building he had evacuated.

"...Thank the Lord we all got out safely."