( CNN ) -- West Virginia 's attorney general and state legislators announced Tuesday that they 'd join those investigating a chemical spill that left hundreds of thousands scrambling for safe water , with one senator promising `` there will definitely be a change . '' `` This whole series of events is unacceptable , '' said Senate Majority Leader John Unger , who will be leading the state legislative probe , echoing many others around West Virginia and elsewhere since the crisis boiled up last Thursday . These latest investigations came out the same day that a few thousand more West Virginians were told they could use their tap water again , for the first time in nearly a week . Still , nearly two-thirds of the nearly 300,000 people initially prohibited from using their taps still are waiting for the all-clear . Their headaches and heartaches trace to the leak of several thousand gallons of 4-methylcyclohexane methanol -- a substance used in the coal industry -- from a storage tank belonging to a company called Freedom Industries . That chemical made its way into the Elk River , to a water plant about a mile upstream , then into the water system . Residents of nine counties -- including the one that is home to Charleston , West Virginia 's capital and most populated city -- were urged last week not to use their tap water to do anything except flush their toilets . With its strong odor as the telltale sign , officials warned that they could n't say that the water so many rely on to drink , cook using or wash themselves with was safe . Authorities worked to flush the foul-smelling chemical from the area water system , all while conducting tests that eventually showed it declining . Chemical spill shines spotlight on loose regulation . But it has been only recently some have been told they can use their water , such as the lifting of the `` do not use '' order Tuesday morning for the Southridge/Southside area near Charleston . By Tuesday evening , about 114,000 people were advised it was safe for them to run their taps again -- with more than 180,000 remaining in limbo . And it 's not just individual citizens in their homes who have been affected . Without safe water , schools and many businesses such as hotels , restaurants and more decided to close . Gov . Earl Ray Tomblin 's office said schools would remain closed in four counties Wednesday , leaving about 46,000 students at leisure . Amid this widespread pain , a number of local , state and federal authorities have announced they 're launching investigations intent on getting to the bottom of what happened and holding people , agencies and companies responsible for the spill and possible issues in the response . Investigators from the Kanawha County Fire Department and the state Department of Environmental Protection were among the first at the scene . By the next day , U.S. Attorney Booth Goodwin announced that his office was also looking into what happened , telling CNN that `` even a negligent release of this kind could be a criminal violation . '' Also on the federal side , Environmental Protection Agency investigators went to the scene as did a team from the U.S. Chemical Safety Board . Plus , two U.S. congressmen -- Reps. Henry A. Waxman and Paul D. Tonko , Democrats from California and New York respectively -- said in a letter Monday they believe the spill may have exposed regulatory gaps in the country 's chemical control laws . Two new authorities in the state of West Virginia on Tuesday announced their own investigations . Attorney General Patrick Morrisey said in a statement that his office plans `` to get to the bottom of this and ensure that the public knows the truth '' -- including what happened , why and how might it have been prevented . `` We need to make sure this never happens again , and that responsible parties are held accountable , '' Morrisey said of his office 's `` unbiased , independent inquiry . '' And Unger , the Democratic state senator from Berkeley , said the Joint Legislative Oversight Commission on State Water Resources -- which he co-chairs -- is also digging into the `` unacceptable '' ordeal . Among other things , that legislative body will look into who knew what and when , `` and if no one knew , why not . '' `` There will definitely be a change to the way things have been done in the past , '' Unger said . And it 's not just West Virginians who are affected . The Greater Cincinnati Water Works , which serves that Ohio city and parts of four counties in Ohio and Kentucky , will temporarily stop taking water from the Ohio River as a precaution , allowing water that might contain traces of the chemical to pass the city , company spokeswoman Michele Ralston said Tuesday . Two Kentucky water systems -- in Ashland and Russell -- temporarily turned off their valve systems , Dick Brown , a spokesman for the Department for Environmental Protection , told CNN . The move was strictly a precaution since the Elk River is a tributary to the Kanawha , which feeds into the Ohio River . The Cincinnati utility is sampling the Ohio River water and so far has n't detected anything out of the ordinary , Ralston said . The move will not disrupt customers ' water supplies because the company has a two-day reserve and a groundwater plant that can provide even more treated water , she said . Opinion : It 's OK , the water 's safe to flush . CNN 's Matt Smith , Michael Pearson , Jason Hanna , Alina Machado and Meridith Edwards contributed to this report .
NEW : More people are told they can use water ; more than 180,000 still under `` do not use '' order . A state legislator says `` there will definitely be a change '' after last week 's chemical spill . Thousands of gallons of a compound used to clean coal poured into the Elk River . The river is now closed for fishing and boating, but officials say it could reopen in two weeks if all goes well with cleanup efforts.