Jamaica's Prime Minister Andrew Holness announced a state of emergency for St. James Parish on Thursday and deployed the military to the area amid a rise in violent crime.
"UK tourists are now quite rightly concerned about outbreaks of violence and those due to fly out in the coming days are now trying to cancel their trips over safety fears".
The popular holiday hotspot of Montego Bay - home to a string of upmarket resorts - has witnessed a recent spike in gun crime that saw authorities resort to extreme measures.
It advised: "You should exercise caution if you are in the area".
The Foreign Office urged the British tourists to stay in their resorts as major military operations are taking place.
Mr Holness said members of the security forces would be equipped with "extraordinary powers" to deal with the situation. "If you do travel outside these perimeters, use transportation arranged or provided by the resort", the advisory says.
The parish of St James is the central focus of the national security apparatus because 335 murders were recorded there last year, and wanton, bloody atrocities associated with gang activities have continued there into this year.
"The declaration of a State of Public Emergency does not mean the suspension of the rule of law".
The child escaped unhurt while the others are now in hospital.
Worldwide travel expert Nick Harris of Simpson Millar solicitors said: "UK tourists are now quite rightly concerned about outbreaks of violence and those due to fly out in the coming days are now trying to cancel their trips over safety fears". The state of emergency allows law enforcement to search businesses and recreational areas that are under a temporary curfew without a warrant.
The US State Department's Jamaica travel advisory was posted on January 10.
The country - which still has the death penalty - has been plagued by high rates of murder and violence.