The police identified the fatalities as Brendon Arcenal Cabanes, 26, and his cousin, Romeo Cabanes, 27.
Confined in the hospital were Winston Campo Bacolod, 26, and Lemuel Macaraya, 30.
The four were workers of a private company, which was subcontracted by the Talisay city engineering department to declog the manhole that would overflow during heavy downpour.
Brendon and Romeo were on their way out of the manhole after cleaning it about 2 p.m. on Thursday when Romeo fell, said Vince Monterde, Talisay City information officer.
But Brendon went back to help his cousin but the two were suffocated and failed to get out, said Monterde.
Bacolod and Macaraya went into the manhole to help Romeo and Brendon but they could not take the stench inside that they had to climb out and get some air.