A water ban entered its third day in northwest Ohio on Monday as the mayor of the U.S. state's fourth-biggest city extended an advisory pending further testing. Tests conducted by both the state and federal Environmental Protection Agency (EPA) showed high levels of toxin levels in two Toledo neighborhoods, Mayor Michael Collins said early Monday. Instead of isolating the two neighborhoods, Collins said he would maintain the ban on drinking or using tap water in the entire city until additional retests are completed. "A majority of areas are satisfactory, but we have two areas of concern," he told reporters. As many as 400,000 people were told not to drink, cook with, or boil the tap water after a toxin called microcystin was found in the Toledo water supply on Friday. The city's drinking water comes from Lake Erie, where a harmful algae bloom that causes microcystin has been growing. About two-thirds of the Toledo-area population is affected by the water warning. Ohio Governor Jahn Kasich issued a state of emergency for three counties. The potential contamination also affects four municipalities in the neighboring state of Michigan. There have been no reports of anybody getting sick from the contaminated water, officials said.