Texas Gov. Rick Perry said Tuesday it's not wise to speculate about what caused an explosion and massive oil spill in the Gulf of Mexico, and he defended his use of the term "act of God" to describe the disaster.

Perry said Tuesday the phrase — which he used in a speech in Washington, D.C., on Monday when discussing the spill — is a legal definition and that his point is "nobody knows what happened" at the oil rig off the Louisiana coast. The undersea well has been spewing 200,000 gallons of oil a day.

The giant oil slick is threatening the Gulf Coast from southeastern Louisiana to Florida. Rig operator BP PLC has been trying unsuccessfully to cap the leak, which began April 20.

"If you will go look up the definition of 'Act of God,' we've used it in legal terms for a long time in this state," Perry told reporters outside the Texas Capitol.

"It may be an accident and it may be something else," he said.

The Democratic group Lone Star Project criticized the Republican governor's remarks as "detached arrogance."

"Eleven men died when the drilling platform exploded. Hundreds of miles of coastland could be damaged for years and even decades. The families of those who died and the victims of the environmental damage deserve a full accounting for the human errors that caused the failure at the rig, the death of loved ones and the spoiling of our Gulf coastline," said Matt Angle, director of Lone Star Project.