Residents said FBI agents spent several hours in the neighborhood showing photos of the suspects and seeking information. They said the men had lived in the area for about a year.
Benjamin Williams, 17, said the group sometimes had young children with them. At times, he added, the men "would cover their faces. Sometimes they would wear things on their heads, like turbans."
Managers of the Sears Tower, the nation's tallest building, said in a statement they speak regularly with the FBI and local law enforcement about terror threats and that Thursday "was no exception."
Security at the 110-floor Sears Tower, a Chicago landmark, was ramped up after the Sept. 11 attacks, and the 103rd-floor skydeck was closed for about a month and a half.
"Law enforcement continues to tell us that they have never found evidence of a credible terrorism threat against Sears Tower that has gone beyond criminal discussions," the statement said.
In Chicago early Friday, people headed to work in the Sears Tower knew about the potential threat but didn't plan to change their routines.
In addition to Batiste and Augustin the defendants were identified as Patrick Abraham, or "Brother Pat"; Stanley Grant Phanor, or "Brother Sunni"; Naudimar Herrera or "Brother Naudy"; Lyglenson Lemorin, also known as "Brother Levi" or Brother Levi-El"; and Rotschild Augustine, or "Brother Rot."
The indictment described the alleged scheme this way:
Joseph Phanor, the father of defendant Stanley Grant Phanor, said he didn't believe "anything they say about" his son being involved in a terrorist plot.
"This boy, he's not a violent boy. He never got into trouble. ... He didn't want to kill people," the elder Phanor told The Associated Press.
He said his son and his friends studied the Bible together in Miami. "All I know is that they have a construction job there and they have a contract to do some construction job. That's what he told me," he said.
The person they believed to be an al-Qaida representative gave Batiste a digital video camera, which Batiste said he would use to record pictures of the North Miami Beach FBI building, the indictment said. At a March 26 meeting, it went on, Batiste and Burson Augustin provided the "al-Qaida representative" with photographs of the FBI building, as well as video footage of other Miami government buildings, and discussed the plot to bomb the FBI building.
But on May 24, the indictment said, Batiste told the "al-Qaida representative" that he was experiencing delays "because of various problems within his organization." Batiste said he wanted to continue his mission and his relationship with al-Qaida nonetheless, the document said.
Associated Press writers Kelli Kennedy and John Pain in Miami and Connie Cass in Washington contributed to this report.