Colombia ? Colombia’s electrical grid collapsed Thursday, causing a nationwide blackout that briefly halted stock trading, trapped people in elevators and left authorities struggling to determine the cause.

By midday, power was slowly being restored to homes and companies, and the north of the capital – home to many company headquarters – was back to normal.

President Alvaro Uribe said the blackout, which began at midmorning, “appears to have affected the entire country.”

Luis Alarcon, manager of state-controlled electricity distributor ISA, issued a statement that the power outage apparently began with an undetermined technical glitch at a substation in Bogota and quickly spread to the rest of the country.