Police are using security and cellphone video to locate a man who vandalized Pablo Picasso's famous painting, "Woman in a Red Armchair," at a museum in Houston.

A fellow museum patron's cellphone camera caught the moment when a man at Houston's Menil Collection, which hosts nine Picassos, vandalized the 1929 painting. The painting was doused with gold spray paint in the image of a bull and the word "conquista," according to police, who said the vandal then fled.

"I'm shocked that he just did it, and unabashedly just ran up and did it," teacher Isaias Torres said .

Museum officials say the crime occurred last week.

The museum staff houses a conservation lab on site and workers are racing to clean the painting. Museum spokesman Vance Muse told the Houston Chronicle that "repair work began immediately" and that the painting "has an excellent prognosis."

Art collector Matthew Hewitt said, "It's excellent that it can be repaired for historic reasons, it's excellent that it can be repaired, for the respect of Houston, for the defamation of any kind of historical art, and the name of Picasso."

The museum was unable to estimate the painting's worth, but similar Picassos have sold for tens of millions of dollars. No arrests have been made.

Anyone who witnessed the attack or has information is asked to call (713) 308-0900.