The three were on duty at the isolation ward of District Hospital, Bishnupur, he said.
"Their reports were received last night. It is not comfirmed yet whether they contracted the disease while on duty or from COVID-19 positive patients outside the hospital," Chief Medical Officer of District Hospital, L Gojendra, said.
Samples of their family members would be examined, he said, adding, containment measures have been put in place.
Manipur has a total of 591 active coronavirus cases, while 250 patients have recovered, officials said.
Tamenglong district, with 83 patients, tops the list of COVID-19 cases in the state. CORR RBT RBT