About 400 people, many holding lit candles, prayed Sunday evening for a safe outcome in the disappearance of 6-year-old Isabel Mercedes Celis as the search for her continued for a second day.

Tucson Police Chief Roberto Villaseñor called her case suspicious and a possible abduction.

"We've used just about every resource we could find to try and locate Isabel," Villaseñor said at a news conference Sunday afternoon at a shopping center on the southeast corner of South Craycroft Road and East Broadway, where friends of the family gathered to pray.

Valerie Ballesteros, one of the vigil organizers and who works with Isabel's mother, said, "Children are a true blessing ... we have to give Isabel back to the Celis family."

Villaseñor said he could not provide new information on Isabel's case, but he said a multi-agency force had scoured a 2.5-mile radius looking for clues.

Investigators have "no definitive break-in" at the home, but they did locate some "suspicious circumstances surrounding a potential entry point," said Sgt. Maria Hawke, a Police Department spokeswoman.

Several search warrants were served at various locations, but Villaseñor declined to say what the searches revealed.

At this time, investigators are "not ruling out anything," Hawke said. She would not say if any materials were taken by investigators from the family's home.

Hawke did say there are "no names of suspects connected to this case."

Villaseñor said the investigation has not narrowed and that every possible scenario is being pursued.

Law enforcement teams have looked in buildings and in the open desert, conducting a "thorough, methodical search," and investigators are sorting through tips and leads, Villaseñor said. He said teams have revisited locations and have conducted interviews, but he declined to elaborate.

The search will continue today. Villaseñor said up to 250 officers worked on the case over the weekend.

Sex offenders living within a three-mile radius of Isabel's home have been interviewed by investigators, which is standard protocol, he said.

The family of Isabel, known as "Isa," told police the child went to bed at 11 p.m. Friday, and when a family member went to wake her up at 8 a.m. Saturday she was gone. The family did a quick search of the house before calling 911 to report her missing.

Isabel lives in the 5600 block of East 12th Street, near East Broadway and Craycroft Road, with her parents and two older brothers. The family is cooperating fully with the investigation, said Hawke.

The Rev. Miguel Mariano, pastor at St. Joseph Catholic Church, 215 S. Craycroft Road, where the family attends Mass, prayed with the family in solitude. "I assured the family they have the parish community's support and prayers. We are one with them in their time of distress," Mariano said.

The family is "emotionally distraught," and their faith is helping them through the ordeal, said Mariano. He described the family as "very quiet and private."

The schools that Isabel and her siblings attend will have counselors available to students, faculty, staff and parents, according to Bud Stewart, superintendent of the Academy of Tucson Schools.

Isabel attends the Academy of Tucson's elementary school, and her siblings attend the middle and high schools.

The schools will keep their schedule, and students and staff will not be interrupted, Stewart said in press release.

Scores of police officers scoured Isabel's neighborhood all day Saturday, stopping anyone who came or went and checking inside cars and trunks. They also handed out fliers with Isabel's photograph and asked neighbors to be on the lookout for her.

Family, friends and volunteers had posted about 10,000 fliers with a picture of Isabel across the city by Sunday morning. She is shown wearing a dark blue uniform, holding a recognition certificate from her school.

The FBI sent agents and an evidence-recovery team to help in the search. A special FBI search dog arrived Sunday from Quantico, Va., to help.

The U.S. Marshals Office is helping in the search, and the Arizona Department of Corrections sent bloodhounds. Both the Pima County Sheriff's Department and the multi-agency Rapid Response Team sent search-and-rescue personnel. The Tucson Fire Department provided equipment and personnel.

Authorities did not issue an Amber Alert on Saturday because they said they were uncertain whether the child was abducted or walked away from her home. Federal guidelines require that law enforcement confirm that a child has been abducted before issuing an Amber Alert; the fear is that false alerts will make people stop taking the system seriously.

Also, in an Amber Alert, authorities must have the identity of a suspect, a description of the vehicle the child is traveling in and the location of travel - none of which fits Isabel's case, Hawke said.

At the vigil, people prayed the rosary and consoled one another.

"Tonight when you go home, give your kids an extra hug, an extra kiss," organizer Ballesteros said.

Friends opened an account for the Celis family. Ballesteros said the public can donate money to the family through Tucson Medical Center at https://www.tmcaz.com/TMCFoundation/

David Andrews, a co-worker of Isabel's mother, said she takes care of everyone else's children, and that he and others came to support the Celis family.

"Isa, we're looking for you, baby girl. We love you," he said.

Contact reporter Carmen Duarte at 573-4104 or cduarte@azstarnet.com