MEXICO CITY (AP) — Mexico City officials said Tuesday they will tighten rules for children leaving government schools on their own after a 7-year-old girl was found murdered over the weekend.

In Mexico City, even grade-school students often simply walk out of school after classes to meet parents waiting on the sidewalks, but there have been few controls to ensure someone is there to meet them.

That is apparently what happened to Fatima, who was seen on video leaving her school on Feb. 11 with an unidentified woman. Mexico City prosecutor Ernestina Godoy said the girl “recognized her, and so they let her go with her.”

Her body was found wrapped in a bag and abandoned in a rural area on Saturday. By law, prosecutors don't give the full name of victims.

Humberto Fernandez, the head of the city's school system, said there is already a little-used rule requiring parents or designated person to show up within 20 minutes after classes, or their kids will be taken to a prosecutors' office.

Fernandez said that rule was “very rarely”enforced because children were accepted at only one downtown prosecutors'office in the city of 9 million. Fernandez said all prosecutors'offices in the city's 16 boroughs will recieve children, and police patrol cars will be obliged to help school officials take them there.

Mexico City Mayor Claudia Sheinbaum said authorities would now issue amber alerts and start searching for children as soon as they are reported missing by a relative or teacher. Authorities lost a full day in the search for Fatima because they waited for a formal missing-person case file to be opened.

Family and neighbors packed a street in the southern borough of Tlahuac on Tuesday for a Mass underneath a massive yellow tarp strung from roof to roof.

The priest leading the service read a message from Bishop Andrés Vargas Peña that acknowledged the indignation felt and urged them to not grow accustomed to the daily atmosphere of crime.

Mourners ate plates of a dish called romeritos on white plastic tables set up in the street outside the home. Votive candles spelled out the girl's name on the sidewalk outside the home.

Marisol Mercado Angeles, a 33-year-old homemaker, held an umbrella to shield her face from the beating sun.

“We're without words,” said the mother whose son attends the same school. “It's something as difficult as it is painful.”

“There's no security at the school,” Mercado said. “I think it is responsible, the school.” She was critical of police and borough authorities as well, who she said only come around when they want your vote.

The lower house of Mexico's Congress held a moment of silence Tuesday for Fatima, whose case has sparked outrage.

The cause of death has not been released. Five people have been questioned in the case, and video footage of her abduction has been shown on television.

Guillermo Anton Godínez, the girl's 65-year-old grandfather, said Monday that his daughter, the girl's mother, arrived at the school 15 or 20 minutes after the woman led the girl away.

On Tuesday, he said the school was negligent and that he knew of cases last year where police were called to pick up kids whose parents were late.

“The cheapness of not spending 5 pesos to call a police car,” he said. “Tomorrow who is it going to be?” He said police should be present at the school for drop off and pick up.

Anton said the prosecutor's office had told him they would throw all their resources at the case and follow it wherever necessary.

He said he didn't recognize the sketch authorities released of the woman who led the girl away from the school and he was sure she wasn’t from this tightly knit neighborhood of low cinder block homes.

“We know each other here,” he said.

Prosecutors' spokesman Ulises Lara offered a $100,000 reward for information on the person who picked her up when she left school.

The abduction and killing of the child came just days after Ingrid Escamilla, a young Mexico City resident, was allegedly murdered by a boyfriend.

The man, who has been arrested and purportedly confessed to killing Escamilla with a knife, mutilated her body and flushed part of her corpse into the sewer.

The Mexican capital has seen a series of angry demonstrations over killings of women over the past few months, including several in which protesters have vandalized major monuments and buildings.

The killings have proved a politically difficult issue for President Andrés Manuel López Obrador, who who has sometimes complained that protests over the killings were an attempt to distract attention from his social programs.