At least 11 people are missing in the collapse of a high-rise apartment building in Medellin, the capital of the northwestern Colombian province of Antioquia, officials said Sunday.

Using specially trained dogs and heavy machinery to remove the rubble, authorities are continuing the search for the missing people in the remains of the Space Building, which collapsed on Saturday night.

Tower 6 of the Space Building collapsed at 8:20 p.m. Saturday and the tragedy was not worse because the apartments inside had been evacuated on Friday when cracks had appeared in the structure.

After the collapse of the 22-story structure, authorities were able to rescue two people identified as Yamid Lopera and Adrian Lopez from amid the ruins. Both were transported to local hospitals where they are being treated for their injuries.

Initially, local officials were speaking of between 15 and 20 people missing, a figure that the interim mayor of Medellin, Claudia Restrepo, reduced late Saturday evening and which the latest report from Sunday morning set at 11.

The apartments in the collapsed tower, which had been recently erected, cost between 200 and 500 million pesos (between $106,000 and $266,000).

After the evacuation of Tower 6, the CDO construction firm, which is responsible for the project, issued a statement saying that the cracks had appeared due to an "unusual failure" on the fourth floor and that there was no risk to the rest of the building. EFE