MANAGUA, Nicaragua –  Outside experts are raising doubts about whether a 39-foot crater found in Nicaragua’s capital this weekend was caused by a meteorite strike, as the country’s government has said.

The U.S. National Aeronautics and Space Administration says the lack of any witness accounts of a fireball lighting up the nighttime sky suggests something else was behind the blast around midnight Saturday.

Bill Cooke is head of NASA’s Meteoroid Environment Office. He estimates the crater shown in photos was likely caused by an explosion roughly the energy equivalent of 1 ton of TNT.

Cooke said Monday that any space rock capable of leaving a hole that size “would have generated a very bright fireball.”

Nicaragua’s government said the previous day that a relatively small meteorite was responsible for the crater.