HOUSTON -- There's still no sign of the son of a Michigan Congressman reported missing in Houston.

Houston Police say 21-year-old Carl Conyers, a UH student, was last seen Tuesday afternoon by his roommate at their apartment in the 3700 block of Southmore.

He is the youngest son of longtime U.S. Representative John Conyers and his wife, Monica.

Monica Conyers flew to Houston from Michigan Thursday afternoon to help with the search.

"This is not like him. If he was going to go somewhere and take a break, which he's never ever done, he would call me," she said. "I've heard nothing from my son. Nothing Period."

Carl Conyers' roommates tell us the last time they saw him Tuesday night, he seemed stressed and said he had a crazy day.

"He was cooking. I greeted him. I noticed he was hiding his face a little bit," said Chat Ball, a roommate. "I didn't think much of it, just because of the fact that school can be hard on a person. Stress is very serious."

Conyers' roommates discovered he wasn't in his room Wednesday morning, but he left his phone, wallet and car behind.

Conyers' girlfriend said he sent a tweet asking her to meet him at UH Wednesday, but he never showed up.

The family was notified and they called police.

Texas Eqqusearch volunteers joined the search Thursday afternoon.

"Did he leave on his own? Who knows?" said Eqqusearch founder Tim Miller. "We have one fact. The fact is that he's missing. We feel that he is certainly in danger one way or another."

Conyers, a UH student, is described as a black male, about 6 feet tall and 145 pounds, with black hair and brown eyes. Police say he has shaven the beard he’s seen wearing in a handout photo.

Conyers' Twitter account indicates he's the President of the Black Business Association at UH and is the marketing director for the Uncommon Colors organization. He's in the class of 2018.

Anyone with information on Conyers’ disappearance is urged to contact Houston Police at 713-884-3131, or the Houston Police Missing Persons Division at 832-394-1840.

"Just pray. Be on the lookout," said Daisha Lewis, Conyers' girlfriend. "If you're watching this, please come home. No one's mad at you. We just miss you."

John Conyers, an 87-year-old Michigan Democrat, has been in Congress since 1965 and is the longest-serving member of the House.

(CBS News Detroit contributed to this report.)