While shootings were heard throughout the city, activists said it was concentrated in the Baab al-Sebaa neighborhood Thursday, al-Jazeera reported.
"Many gunmen on the streets [are] shooting randomly," a witness told al-Jazeera.
Witnesses also said gunfire prevented people from removing some of the injured and dead in the streets.
Human rights activists, claiming more than 50 people have been killed in Homs since the weekend, said some of those arrested were key players in protests seeking the ouster of President Bashar Assad while others were residents randomly detained.
Human Rights Watch, meanwhile, said Syrian security forces have intensified their campaign of mass arrests in cities that have had anti-government protests. The targeted cities include including Hama, Homs and several Damascus suburbs.
Reliable activists and witnesses contacted by Human Rights Watch estimate since late June, security forces arrested more than 2,000 anti-government protesters, medical professionals treating wounded protesters and people allegedly providing information to international media and human rights organizations, the organization said in a release.
"President Assad talks reform but continues to practice repression, not only through the widespread killings of demonstrators but also through mass arrests," said Sarah Leah Whitson, Middle East director at Human Rights Watch.