Up to 8,500 US troops have been put on heightened alert to deploy as Russian troops mass on Ukraine's border, Pentagon spokesman John Kirby said Monday.

US Secretary of Defense Lloyd Austin issued the prepare to deploy orders at the direction of President Joe Biden.

Kirby said no final decision to deploy the troops had been made.

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Wall Street was deep in the red again Monday as investors feared the Federal Reserve's plans to hike interest rates would eat into corporate profits. The tensions in Ukraine, earnings season and — of course — inflation weren't helping, either.

The Dow Jones Industrial Average fell 1,000 points, or 3%, at midday.

The S&P 500, the broadest measure of the US equity market, was trading 3.7% lower at midday. Last week, the index logged its worst week since March 2020.

The Nasdaq Composite was the biggest loser of the morning, trading down 4.5%. 

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A lone gunman injured several people in a shooting in an auditorium at the University of Heidelberg, in south west Germany on Monday, police said.

A police spokesman told CNN that the perpetrator, described as a young man, was dead. His cause of death is not known.

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The State Department announced on Sunday night that it will be reducing staff levels at the US Embassy in Kyiv, Ukraine, beginning with the departure of nonessential staff and family members.

"On January 23, 2022, the Department of State authorized the voluntary departure of U.S. direct hire employees and ordered the departure of eligible family members from Embassy Kyiv due to the continued threat of Russian military action. U.S. citizens in Ukraine should consider departing now using commercial or other privately available transportation options," the State Department said in a statement.

CNN reported on Friday that the embassy had requested that the State Department take this step as Russia has continued to mass forces and equipment near Ukraine's borders, sparking fears of a renewed invasion.

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Before taking his own life, Brian Laundrie wrote in a notebook he was responsible for Gabby Petito's death, according to the FBI.

"A review of the notebook revealed written statements by Mr. Laundrie claiming responsibility for Ms. Petito's death," the FBI's Denver Field Office said in a statement released Friday.

The notebook was discovered in October, in the same area as Laundrie's remains, in Florida's Myakkahatchee Creek Environmental Park, authorities said.

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