President Barack Obama on Thursday ordered federal agencies to review safety rules at chemical facilities in response to the deadly April explosion at a Texas fertilizer plant.

In an executive order, Obama tasked agencies with identifying new ways to safely store and secure ammonium nitrate, the explosive chemical investigators say caused the blast. Agencies are also being told to determine whether additional chemicals should be covered by federal regulatory programs.

The massive explosion at the plant in the community of West, Texas, killed 15 people, leveled hundreds of structures and damaged three of the town’s four schools. It also prompted new scrutiny of regulations at chemical plants and the risks posed by deadly chemicals to people living in surrounding areas.

While the explosion is still being investigated, preliminary findings have been presented to Congress. A report sent to the Senate Environment and Public Works Committee in June showed that the decades-old standards used to regulate fertilizer chemicals are far weaker than those used in other countries.

The report concluded that the safety of ammonium nitrate fertilizer storage “falls under a patchwork of U.S. regulatory standards and guidance — a patchwork that has many large holes.”

The Environmental Protection Agency, for example, does not regulate the chemical. The Occupational Safety and Health Administration requires that ammonium nitrate be stored separately from other combustibles in a room that has a partition that can withstand fire for up to an hour. But the agency had not inspected the West plant since 1985.

Democratic Sen. Barbara Boxer of California, chairwoman of the Senate committee, said she discussed the problem with Obama last week and was gratified he took the executive action.

“As I told the president, the EPA has not updated its alert since 1997, and the best practices recommended by other federal agencies such as OSHA are not being uniformly followed,” she said in a statement.

Some agencies do have rules on ammonium nitrate, but none apparently applied to the facility in West.

With the investigation continuing, the White House said it wanted to move forward where it could to address chemical safety concerns. Obama’s executive order also calls for improved coordination among state and local agencies that deal with chemical plants. And it tasks the federal government with modernizing its information sharing about the plants.

(AP)