The striker damaged his right foot during his first full training session since regaining his fitness from a heel problem and will now see a specialist
The club have revealed that the damage is in the same part of his right foot as his previous injury and the striker will now be examined by a specialist.
West Ham have given no timeframe regarding Carroll's absence.
The 24-year-old was forced out of England's post-season friendlies in May with a heel injury and has yet to make an appearance for Sam Allardyce's side this term.
Following a season-long loan spell at Upton Park where he scored seven goals in 24 Premier League games, Carroll completed a permanent move from Liverpool to West Ham in June.
Allardyce is continuing his efforts to sign another striker, with the club reportedly competing with Arsenal for Romania striker Ciprian Marica, who was released by Schalke this summer.
Carlton Cole, who was not offered a new deal by West Ham at the end of last season, has also been on trial with Allardyce's side.
West Ham have also been linked with a move for former Fulham forward Mladen Petric, who is currently available on a free transfer.