The move came yesterday on the final day of a three-day trip by Zhang Dejiang, who chairs China's communist-controlled legislature, for which frustrated protesters have been kept out of sight behind barricades in a security lockdown.
Zhang's visit was the first by such a senior official for four years and comes as concerns grow that freedoms are under threat in semi-autonomous Hong Kong as Beijing tightens its grip.
Police chased a group of five protesters, including Wong, yesterday as they ran along a major highway in eastern Hong Kong which had been cleared for Zhang. They were carrying a sign calling for "self-determination".
They were detained before Zhang's motorcade emerged from a tunnel.
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"The five arrested persons were released on bail and will need to report back to police in mid-June," a police spokeswoman told AFP, adding that charges had not been laid.
They were arrested for "obstructing police officer in the execution of duty and disorderly conduct in a public place", she said.
Demosisto said Wong, who already faces two imminent verdicts and a possible prison sentence for protests in 2014, was released on a HK$500 (USD 65) bail.
Wong faces charges of taking part in an unlawful assembly and inciting others to do so, which carry a jail term of up to five years.
The 19-year-old has always argued that the cases against him are political persecution.
Hong Kong is semi-autonomous after being returned to China by Britain in 1997, with much greater freedoms than seen on the mainland.
But there are fears those freedoms are being eroded by increasing interference from Beijing.