DETROIT (AP) _ A loading dock fire early today at the Cobo Hall convention center threatened to cut short one of the city's major conventions.

The fire broke out shortly after midnight on the dock near the hall, where the Society of Automotive Engineers has drawn 50,000 visitors for its annual International Congress & Exhibition over the past three days.

The fire was brought under control in about 90 minutes, said fire department Battalion Chief Tim McConnell. No serious injuries were reported.

Investigators planned to start looking for the fire's cause today, but flames rekindled and firefighters were called back at about 6:30 a.m., department spokesman Lee Moore said.

The fire generated thick smoke, caused part of the loading dock's roof to collapse and melted metal skirting on the hall's exterior.

Officials canceled today's morning events and were undecided about afternoon programs.

There was no fire damage to the exhibits.