Image copyright Reuters Image caption Hunter Harrison took up the top job at CSX in March

Hunter Harrison, the CEO of the US transportation company CSX, has died just days after going on medical leave.

Mr Harrison, 73, died in Florida due to "unexpectedly severe complications from a recent illness", the company said.

The company's shares fell sharply in trading on Friday after Mr Harrison's leave was announced.

CSX is the third largest railway company in the US, and owns a network connecting every metropolitan area in the eastern US.

CSX said that Jim Foote would continue as acting CEO.

Mr Harrison, who joined CSX in March, had ambitious plans to change CSX.

He had a long career transforming railway companies, with stints at the helm of Illinois Central, Canadian National and Canadian Pacific.