Investigators have determined that the construction site of a downtown St. Paul hotel was intentionally set ablaze last week, and they believe no one died in the early-morning fire.

The Bureau of Alcohol, Tobacco, Firearms and Explosives called in a special team to help investigate the source of the fire that broke out Aug. 4 at the site of the $68 million Seven Corners Gateway project on W. 7th Street, across from the Xcel Energy Center.

"After investigating the scene, reviewing video footage and talking to numerous witnesses, fire investigation experts ruled the fire to be incendiary, or intentionally set," the ATF said Tuesday in a statement.

Authorities also talked to local homeless shelters to account for missing people, and they brought in construction equipment and a cadaver-sniffing dog to search the rubble. After a four-day search, they found no human remains.

Construction started on the project last November. The fire erupted about 4:20 a.m., with most damage hitting a five-story, 120-room Courtyard by the Marriott hotel site.

"While it is infuriating to think people would choose to burn down a building and endanger innocent lives, I am more saddened for the citizens of this community who will have to deal with the anxiety and fear this type of act may leave behind," said Carl Kaeding, president of Kaeding Development Group.

The ATF will continue to investigate, alongside the Fire Department, the Police Department and the Minnesota State Fire Marshal Division, and in conjunction with federal prosecutors.