As the crowd scattered, police quickly apprehended the suspect, whom they identified as a man from Inner Mongolia with the last name Jiang. The blast hurt his hand, authorities said.
A probe into his motives is underway.
The explosion happened about 1 p.m., multiple witnesses said.
Liang Zhou, 21, said she was waiting to apply for a student visa when she heard a bang.
“It sounded like a gas tank exploded,” said the woman in black Vans sneakers. She dashed away through the white smoke.
Zhang Lisi, 47, was waiting outside for her son, a college junior who needed a visa to resume his studies in Riverside, Calif., when the bomb went off.
She figured it was a car accident.
“It sounded like a car tire had blown,” Zhang said.
Word of a blast near the embassy spread quickly on social media. Photographs and videos posted online showed smoke near the embassy’s eastern edge, as well as security personnel and police cars gathered near a nearby intersection.
But less than an hour later, the scene was largely clear and the embassy was again open for business. More than a hundred people stood outside, some unaware that a bomber had recently ignited a device less than 100 meters away.
Only a trail of blood remained on the sidewalk. Onlookers crouched around the droplets, snapping photos on their phones.
Police told reporters to leave.
As rumors swirled Thursday, the Global Times, a Communist Party-controlled newspaper, reported there had been an attempted self-immolation at the same spot at 11:00 a.m., briefly creating confusion about what took place. It is unclear whether that incident occurred. Local police have not commented.
With the U.S. school year around the corner, Chinese students are busy finishing up paperwork so they can start classes in the fall.
Determined applicants Thursday said they were shaken but returned to stand in the 90-degree heat.
Liang, who is headed to California, said she needed her paperwork by Friday.
“The explosion scared me,” she said, “but this is my last day in Beijing.”
Luna Lin and Amber Ziye Wang contributed to this report. Rauhala reported from Almaty, Kazakhstan.