MILWAUKEE (REUTERS) - A number of soldiers have been injured on a US Army base in California when a military helicopter blew over a tent during an annual training exercise, the base said.

Some 22 injuries were reported after a US Army UH-60 Blackhawk helicopter landing rotor wash caused a tent to collapse at about 9.30pm on Wednesday (July 18) at Fort Hunter Liggett in Monterey County, about 250 miles (400km) north-west of Los Angeles, the base said in posts on Twitter and Facebook.

Four of the injured were taken to hospitals, but the majority of the injuries were minor and were treated at the scene, the US Army base said.

It was not immediately clear how many of those injured were soldiers, with the base just saying "a number" had been hurt. No fatalities were reported, it said.

The base said the incident occurred during an annual US Army Reserve exercise for Army Reserve and Army National Guard soldiers.