"She was missing, and everyone was worried about her, trying to find this innocent girl, but we had no good luck," said Gao Qin, 23, a law student from Shanghai, who was following alerts on Facebook and on the Chinese equivalent of Twitter. "We were all expecting she was OK - maybe injured, lying on a bed in a hospital."
On Tuesday, students here said, dean of students Kenneth Elmore confirmed in a message that a student had died, but did not release Lu's name at her family's request. Her hometown Evening News reported Lu as the third person killed and said the woman's father had confirmed her death.
"At first, everybody was sad," Qin said as he stood near the makeshift memorial. "Then we are angry - how could somebody do this?"
Lu was known as a "fun and lovely" person, he added.
On her Facebook page, Lu's profile photo shows her boldly looking over her shoulder at the camera, a big pom-pom purse on her shoulder and a half-smile on her face. She discusses her travels - Rhode Island, New Hampshire - and her likes, which included the Economist magazine, Disneyland, and the Boston Symphony.
"I love the Charles River at night," Lu wrote.
She posted a series of photos headlined "New Beginning in BU." It included pictures from an outing to Toah Nipi, a retreat near Boston that calls itself "a place to come away, meet God, and be renewed."
Lu's Facebook page disappeared Wednesday afternoon, even as another emerged titled "R.I.P. Lu Lingzi."
She graduated in 2012 from the Beijing Institute of Technology. At BU, she belonged to the Chinese Student Scholar Association, which promotes academic exchanges and friendship.
A Facebook statement from the group said it had no comment. Another posting read, "Your heart will always be with us."
Commonwealth Avenue is a main route through campus, and the plaza was crowded Wednesday, students gathering on a clear, cool New England afternoon. The base of a monument to the Rev. Dr. Martin Luther King Jr. became the place where people memorialized Lu.
Joy Liu, 23, a first-year journalism graduate student, left the green hat and shamrock. "From Boston and Beijing, with love," her note read.
She did not know Lu, but works for the school news service and had visited Boston Medical Center on Tuesday night to get information. Lu was then still reported as missing, having watched the marathon from near the finish line, and another graduate student was being treated for serious injuries.
Students from the Chinese association were at the hospital looking for Lu, she said. Her absence had been reported to the Chinese Consulate in New York about 12 hours after the explosions.
Another journalism graduate student, Kiva Kuan Li, said she tried to console a close friend of Lu's between classes Wednesday. "If I mentioned her name," she said, "he would begin to cry."
In the plaza, Robert Allan Hill, dean of Marsh Chapel, prepared for an evening "Service of Healing" to honor and remember all those killed and injured. He was working with Chinese students.
"They are going through this with faith, courage, and resilience," Hill said. "This is hard for them. They are taking care of each other and going through it together."
A special gathering to remember Lu will be Thursday evening at Agganis Arena.
China is by far the largest sender of international students to the United States, with 194,029 here in 2011-12. That's 25 percent of all overseas students, according to the Institute of International Education.
Massachusetts ranks fourth among states in international students - with Chinese the largest population.
Outside the chapel late Wednesday afternoon, the plaza quieted, and the crowd of students thinned.
Lindsey Popper, a divinity student, came out to set down two vases of flowers.
The sun was beating on the others, she noted. She didn't want there to be dead flowers.
Contact Jeff Gammage at 610-313-8205 or firstname.lastname@example.org, or follow on Twitter @JeffGammage.