Cuban health authorities urged Havana residents on Sunday to take extra hygiene precautions as they investigate the deaths of eight children from an unknown cause.

A government communique said that there had been an increase in digestive and respiratory illnesses reported over the last two weeks in the Cuban capital coinciding with power, cooking gas and water problems, in part caused by Hurricane Dennis, which passed a few miles east of Havana July 8.

The statement said children were particularly susceptible, and in some cases high fever and other complications developed.

“In this context eight deaths among minors have occurred which are being meticulously investigated,” the communique, broadcast during the government’s nightly television newscast, said.

While children die at high rates in developing countries from various diseases, such deaths are rare in communist Cuba, which takes pride in a relatively well-developed and free health care system.