U.S. President Donald Trump speaks on tax reform at the White House in Washington D.C., the United States, on Dec. 13, 2017. (Xinhua/Ting Shen)

WASHINGTON, Dec. 18 (Xinhua) -- U.S. President Donald Trump offered "thoughts and prayers" on Monday for those involved in a train derailment in U.S. west coast state of Washington.

In a tweet, Trump thanked the first responders who are on the scene, and added that the White House is monitoring the situation.

An Amtrak passenger train derailed on an overpass in Washington state on Monday morning.

A U.S. official said the derailment has killed at least six people and the death count is expected to rise.

In another tweet following the incident, Trump called for a boost to infrastructure spending.

The train accident "shows more than ever why our soon to be submitted infrastructure plan must be approved quickly," the president wrote.

The administration is expected to release a framework for increased infrastructure spending early next year.