12/15/2017 01:00 EST | Updated 12/15/2017 01:20 EST

CSX Corp. says president/CEO Hunter Harrison on medical leave

JACKSONVILLE, Fla. — Florida-based railroad CSX Corp. says president and CEO Hunter Harrison is on medical leave due to what it calls "unexpected complications from a recent illness."

The company did not disclose the nature of that illness.

Harrison, who is in his early 70s, was hired by CSX in March after several years leading both CN Rail and Canadian Pacific (TSX:CP).

He was credited with generating significant profits at both Canadian rail companies by employing tighter train schedules and lean expenses.

Questions about Harrison's health were raised earlier this year when the Wall Street Journal reported that Harrison often works from home and occasionally uses oxygen because of an undisclosed health issue.

CSX says chief operating officer James M. Foote will fill in as acting CEO while Harrison is away.

"On behalf of the board and the entire CSX family, I want to express that our thoughts are with Mr. Harrison and his family," chairman Edward Kelly said in a statement.

Foote called Harrison "an icon in the industry and we pray for his speedy recovery."