He said he saw people pushing and shoving, and women crying.
"My family is inside. I cannot enter to see them anymore. I don't know what to do," he said, calling the organization "not very good."
Luis Reyes, a Mexican-American living in Los Angeles, likened the crush to scenes a few weeks ago in South Korea that killed more than 150.
"You can't go back and you can't go forward," he said. "I told my son, 'Let's go outside. It's too dangerous."It wasn't clear if anyone was injured or arrested.
There was a similar situation Saturday night at a pre-World Cup concert as people tried to push their way inside the same fan zone.
Inside the festival area on Sunday there were no signs of trouble as tens of thousands of people watched the opening match. People were dancing, singing and drinking at a concert following the match between Qatar and Ecuador, which was played in the city of Al Khor.
Mahdi Hussain, a 17-year-old who did not manage to enter, said he was not happy that beer was being served.
"That bothers me," he said. "I don't want to be in an atmosphere where there is alcohol."
Samira Said, who moved to Qatar from Egypt about 25 years ago, said she was overjoyed that an Arab country got to host the World Cup.
"As an Arab, I felt honored. I was happy," the 50-year-old said.