BANJA LUKA, Bosnia-Herzegovina — Bosnians struggled Tuesday to comprehend how a 17-year-old known as a gentle boy could kill a teacher, wound another and take his own life in the country's first school shooting.
"All residents are in shock today," said Ostoja Dragutinovic, the mayor of the remote eastern town of Vlasenica, 30 miles northeast of Sarajevo, where Dragoslav Petkovic opened fire Monday in front of 30 terrified students.
Using his father's 7.65-mm handgun, Petkovic shot and killed his history teacher, Stanimir Reljic, 53, outside the local high school — then walked into a mathematics classroom and shot instructor Saveta Mojsilovic, 50, wounding her in the neck. She remained hospitalized in critical condition Tuesday.
Seconds later, the 11th-grader put the gun to his head and pulled the trigger, sending screaming schoolchildren fleeing from a room spattered with blood and pocked with bullet holes.
A classmate said Petkovic had confided the day before that he believed Reljic disliked him and might not give him a passing grade for the year.
The shooting mystified residents of Vlasenica, who never expected the kind of tragedy that has stung American schools and played out four days ago in Erfurt, Germany, where a 19-year-old recently expelled student shot to death 16 people at his high school before killing himself.
"According to the teachers of the school and other residents who knew him, the student who committed this murder was never perceived as a person who was capable of doing such a thing," the mayor said. "He was quiet and not such a bad student."
But Petkovic's friends said his gradually worsening grades appeared to have driven him to despair.
"He complained that the history teacher hated him and might not let him pass at the end of the year," said the gunman's best friend, Ognjen Markovic, 17, who played basketball with Petkovic the day before the shooting.
Authorities and witnesses said Petkovic had approached Reljic outside the school and asked the teacher for another chance to improve his poor marks in history. When the teacher refused, they said, Petkovic opened fire.
The United Nations international police force, which monitors the work of local police in Bosnia, said Tuesday that a special team of local police crime inspectors would be assigned to investigate the shooting.
Vlasenica's school principal, Dragomir Zugic, described Petkovic as "quiet and sensitive," and he told the Sarajevo daily Dnevni Avaz that the boy may have been influenced by the Erfurt shooting.
Police said Tuesday that the teen-ager left a note behind thanking his family for everything they did for him.
"I'm begging my mother to forgive me, and I'm thankful to her for everything she has given me. I'm thankful to my father for all the good advice and to my older brother for the help he always gave me," Petkovic wrote.
He requested his belongings be distributed to six of his friends and asked to be buried in Vlasenica, his hometown.
"Forgive me. People learn from their mistakes," the letter concluded.
The school remained cordoned off with plastic police tape Tuesday and will remain closed until May 7.