Dayspring Church, where one of the slain students, Angelique Ramirez, attended services, provided a licensed counselor for members who needed to talk about the deaths.
"Our objective as a church is to offer hope and healing that we understand only comes through a relationship with Jesus Christ," Senior Pastor Brad Drake said.
Church leaders wore green T-shirts with gold lettering -the colors of Santa Fe High School - that spelled out a verse from Corinthians within an outline of the state of Texas: "We are hard pressed on every side, but not crushed; perplexed, but not in despair; persecuted, but not abandoned; struck down, but not destroyed."
Ramirez was a member of the church's youth ministry, Drake said.
"She was a sweet young lady, had a style all of her own," he said. "She almost always had a new hairstyle."
At Arcadia First Baptist Church, Texas Gov. Greg Abbott hugged grieving parishioners as they arrived. Among them was Monica Bracknell, an 18-year-old senior who survived the shooting. She stopped to tell the governor that the attack should not be turned into a political battle over gun control.
Surrounded by television cameras, photographers and reporters, she told Abbott guns were not to blame.
"People are making this into a political issue," she said she told him. "This is not a political issue. It's not a gun-law issue."
It was not the first time faith in Santa Fe has been tested with the whole country watching. In 2000, the city of 13,000 people was at the center of a landmark U.S. Supreme Court decision that banned students from leading pregame prayer over loudspeakers.
The court ruled 6-3 that the school district's policy of allowing student-led prayers at campus events violated the constitutionally required separation of church and state. Justices said that giving students a public forum for prayer was effectively sponsoring the message.
Also Sunday, Texas Lt. Gov. Dan Patrick called for a "hardening" of the nation's school buildings in the wake of the attack by a 17-year-old student who killed 10 people at a high school near Houston.
Patrick, a Republican, blamed a "culture of violence" and said more needs to be done to keep shooters away from students, such as restricting school entrances and arming teachers.
"When you're facing someone who's an active shooter, the best way to take that shooter down is with a gun. But even better than that is four to five guns to one," he told CNN's "State of the Union."
On ABC's "The Week," Patrick said he supports background checks for gun purchasers but stressed that "gun regulation starts at home."
The first funeral for a shooting victim was set for later Sunday. Services for 17-year-old Pakistani exchange student Sabika Sheikh were to take place at a mosque in suburban Houston.
Her father, Abdul Aziz Sheikh, described his daughter as an accomplished student who aspired to work in civil service and hoped one day to join Pakistan's foreign office. Her body is to be returned to her family in Karachi.
The suspect in Friday's attack began by firing a shotgun through an art classroom door, shattering a glass pane and sending panicked students to the entryway to block him from getting inside, witnesses said.
Dmitrios Pagourtzis fired again through the wooden part of the door and fatally hit a student in the chest. He then lingered for about 30 minutes in a warren of four rooms, killing seven more students and two teachers before exchanging gunfire with police and surrendering, officials said.
Freshman Abel San Miguel saw his friend Chris Stone killed at the door. San Miguel was grazed on his left shoulder by another volley of shots. He and others survived by playing dead.
"We were on the ground, all piled up in random positions," he said.
Galveston County Judge Mark Henry, the county's chief administrator, said he did not think Friday's attack was 30 minutes of constant shooting, and that assessment was consistent with other officials who said law enforcement contained the shooter quickly. But authorities did not release a detailed timeline to explain precisely how events unfolded.
In their first statement since the massacre, Pagourtzis' family said Saturday that the bloodshed "seems incompatible with the boy we love."
"We are as shocked and confused as anyone else by these events," said the statement, which offered prayers and condolences to the victims.
Relatives said they remained "mostly in the dark about the specifics" of the attack and shared "the public's hunger for answers."
The 17-year-old suspect has been jailed on capital murder charges. His attorney, Nicholas Poehl, said he was investigating whether his client endured any "teacher-on-student" bullying after reading reports of Pagourtzis being mistreated by football coaches.
In an online statement, the school district said it investigated the accusations and "confirmed that these reports were untrue."
Poehl said that there was no history of mental health issues with his client, though there may be "some indications of family history." He said it was too early to elaborate.
WATCH: Rainbow over the church in Santa Fe where services will be held to honor victims in deadly school shooting