U.S. Senator Barbara Boxer said on Tuesday she plans to investigate the explosion at a Texas fertilizer plant earlier this month that killed 15 people and injured scores more.
California's Boxer, the head of the Senate Environment and Public Works Committee, said the panel will hold a hearing "in the near future" on the disaster and will probe whether there are any gaps in the enforcement of U.S. chemical safety laws.
The cause of the April 17 fire and explosion at West Fertilizer Co, about 20 miles (32 km) north of Waco, is not yet known.
"I cannot rest until we get to the bottom of what caused the disaster in West, Texas and the tragic loss of life," Boxer said in a statement. "It is critical that we find out how this happened."
A Texas state House committee is slated to hold the first hearing on the explosion by a legislative body on Wednesday in Austin, Texas.
The state panel on Homeland Security and Public Safety has invited testimony from state entities or regulators that oversee rules, security and other details for facilities such as the fertilizer plant involved in the disaster.
Concerns have been raised that the fertilizer plant might have been storing significant amounts of ammonium nitrate, which can be used in bomb making, without notifying the U.S. Department of Homeland Security (DHS) as required by law.
Boxer, a Democrat, sent a letter to the Environmental Protection Agency on Tuesday requesting more information about the agency's oversight of chemical safety.
She questioned why the EPA does not include ammonium nitrate on the list of chemicals that facilities must report to agency under its Risk Management Program.