On Saturday morning, Mira Hu's parents dropped her off at Arcadia High School to take the SAT. Then she disappeared.
A few hours later, police say, Mira, 16, texted her brother with an explanation. She was running away from home, overwhelmed by the pressures of the test and classes at San Marino High School.
A classmate saw the rising senior leaving the testing site before the test began, according to posts on her brother Anthony's Facebook profile. "The proctor says she was absent," the brother wrote.
Surveillance video footage later showed the 5-foot-3, 95-pound girl boarding a Greyhound bus headed for San Francisco, said Sgt. Tim Tebbetts of the San Marino Police Department.
Mira's family hired a private detective and wrote a message to their daughter on a website they created: "We love you Mira," it says. "Please come home."
Mira's parents have declined to comment. But the idea that academic stress might lead a student to take desperate steps is hardly surprising in the San Gabriel Valley.
San Marino High school is one of the most competitive in the state. U.S. News & World Report ranks it among the top 300 in the nation.
In the class of 2014, 90 of 279 students surveyed had a GPA of 4.0 or higher, according to the school's website. The class' average SAT score was 1880 out of 2400. One year, four students got perfect scores.
"Most of the students are taking five AP classes," said Marina Hashimoto, who graduated from the school this year. "The tests are hard. There's a lot of Asians, and they're all really smart."
Students say they have to compete to participate in anything that looks good on a college application — such as the six-week summer classes that aim to give students a head start on the next semester. Many students attend intensive after-school programs at the tutoring businesses that cluster in the neighborhoods around the school.
With so much of student life focused on college admissions, test scores can become gossip fodder, students say. Each year, when the College Board releases SAT scores online, throngs of students gather around smartphones in the school quad and announce their scores as they click on them, said graduating senior Jason Hao, 18.
"When someone gets a high score, they're going to tell everyone," Hao said.
San Marino High officials declined to comment on Mira's disappearance or the school's competitive culture, but students said that this time of year can be particularly stressful: three days of final exams, followed by the SAT, the start of summer school and the mailing of final report cards.
"We don't have time to relax," Hashimoto said.
She added that Mira, who participated in debate and volunteered, was friendly and nice to everyone. She was shocked by the news that Mira had run away.
"She was really smart. I'm surprised she was overwhelmed by school," Hashimoto said. "I think she took a lot of hard classes."
Billy Wu, 15, said parents at San Marino High sometimes have painfully high standards for their children. Billy and Mira both took debate last year, and Billy said she was "very competitive."
"When she lost a round, it would impact her," Billy said. "I feel like it affected her a lot."
Mira attended an international school in China before starting at San Marino in 2012, and she expressed unhappiness in Facebook posts after she enrolled at San Marino High. She wrote of missing her school and friends in China, and at one point announced, jokingly, that she was transferring back to her school in China.
"Life is not filled with ups and downs," Mira wrote. "There are only downs."
Police are still searching for Mira, last seen carrying a large navy blue backpack wearing black jeans and a black jacket. They believe she could be traveling to Northern California to visit UC Berkeley, the college she hopes to attend.
A flier with her name and face has been circulated among law enforcement agencies across the state.
Mira's family has launched a website to help gather information about her whereabouts at www.helpfindmira.com. Her brother reached her briefly on Facebook last night, Tebbetts said.
"He saw her online and sent her Facebook chats until she finally responded with "'I'm safe,'" Tebbetts said.
Those with information about her whereabouts are asked to call San Marino police at (626) 300-0720.