Myung Jae Kim, 56, was acquitted of attempted murder, but was convicted of false imprisonment, assault with a firearm, three counts of assault on a peace officer, possession of a destructive device in a public place, possession of a destructive device for intimidation or injury and making criminal threats.
He was also guilty of sentence-enhancing allegations, including using a deadly weapon and the personal use of a firearm. But jurors rejected the allegation that he intentionally fired a weapon.
Kim faces a maximum of 24 years in prison when sentenced on June 14, Senior Deputy District Attorney John Christl said.
Attorneys on both sides claimed victory.
"I think the victims received justice for the crime," Christl said.
"It was the right result," said Kim's attorney, Kevin Song of the Orange County Public Defender's Office.
Kim, who owns a water purification company, took the employee hostage two years ago in retaliation for money that went missing in his safety deposit box. He claims he lost about $235,000 in cash placed in a safety deposit box at Hanmi Bank in Garden Grove in 2007.
In March 2012, he walked into Saehan Bank at 4542 Beach Blvd. in Buena Park with a white box containing a sawed-off shotgun, four pipe bombs, a lighter, shotgun shells and a knife, prosecutors said.
He took Kwon hostage for nearly four hours before SWAT officers stormed the bank. A shootout ensued, and Kim was hit in the stomach. Kim shot at Kwon, who avoided the gunfire, in response, prosecutors said.
When the money went missing from Hanmi Bank, Kim filed a police report with Garden Grove police. But that case was closed a year later. Bank officials conducted their own investigation and suggested the defendant's wife took the money, Christl said.
But Kim continued to call Kwon to ask about the status of the investigation, even when she transferred to Saehan Bank.
Kim's lawyer said his client would call Kwon once or twice a year and she would tell him there was nothing she could do, Song said.
He added that Kim had told Kwon upon entering the bank: "I need to talk to the vice president of this bank and I need to find out who took my money, and when I find out I'm going to kill myself." Kim called his brother and wife from the bank to say goodbye.
Song also alleges that Kim did not fire at Kwon, but the gun went off when he was hit by police.
"This is a case about a family man desperate for answers," Song told the jury.
City News Service contributed to this report.
