MEXICO CITY (AP) - Cristal Estrada is pacing back and forth with a blanket wrapped around her near the tent where she spent the night on the street in Mexico City's Roma Norte neighborhood.
 
She is worried about her brother Martin, a 31-year-old accountant, who is believed to be in the remains of a seven-story office building across the street that collapsed in Tuesday's earthquake.
 
Estrada says she's frustrated that she can't do anything herself to help remove the rubble. Rescuers continue to say there's life in the wrecked building, but there's no telling whether that includes her brother.
 
Estrada worries that "they do not have much time in there."
 
Officials say scores of people have been rescued alive from collapse buildings, but at least 286 are known to be dead.