Pakistan remains on edge ahead of former prime minister Imran Khan's hearing on corruption charges, a day after his dramatic arrest.
Local media have reported at least two deaths amid demonstrations by his supporters in Pakistan.
Amid the chaos, police said Mr Khan's hearing on Wednesday would be moved to the location where he is under custody.
Police have carried out raids and arrested supporters of Mr Khan's party in the hours since his arrest.
The former international cricket star is facing dozens of charges relating to corruption and sedition, which he says are politically motivated.
Pictures early on Wednesday local time showed lines of officers forming in front of a police building in the capital Islamabad. A police guest house has been declared a "courtroom" for the hearing, a police official told BBC Urdu.
Other photos show scores of vehicles badly burned in Pakistan's largest city Karachi, after overnight protests.
Mobile internet services remain inaccessible across the country. Pakistan's telecommunication authorities said they had suspended services on instructions from the interior ministry.
Schools also remain closed, some highways have been blocked and there is little traffic plying roads in major cities.
Mr Khan's supporters have also taken to the streets in the UK, US and Canada, among other countries, following his detention.
Protests are expected to continue on Wednesday, with some demonstrators planning to march to Islamabad.
"This was last night, the crowds will be bigger today to protect Imran Khan!" Pakistan Tehreek-e-Insaf (PTI) posted on its official Twitter account, accompanied by a clip of a mass protest on Tuesday evening.
Speaking to the BBC's Newshour, Mr Khan's spokesman, Raoof Hasan, said he expected "the worst" and that the arrest could plunge the country "into chaos and anarchy".
"We're facing multiple crises. There is an economic crisis, there is a political crisis, there is a cost of livelihood crisis and consequently this occasion will be a catharsis for them to step out and I fear a fair amount of violence is going to be back."
Mr Khan was arrested on Tuesday while in court in Islamabad to face charges in various graft cases.
Dramatic footage showed dozens of security officers forcibly removing the 70-year-old Mr Khan from court, then bundling him into a police vehicle.
Tuesday's arrest was based on a new warrant for a separate graft case, connected to a case involving the transfer of land for Al-Qadir University, near Islamabad. It is the latest in an escalating political battle between Mr Khan and Pakistan's powerful army.
Many analysts believe Mr Khan's election win in 2018 happened with the help of the military. But now in opposition, he has become on of the military's most vocal critics.
Mr Khan was ousted as prime minister in April last year and has been campaigning for early elections since then. The polls are due to be held later this year.
Hours before the arrest, party officials released a pre-recorded video by Mr Khan, in which he urged supporters to come out in support of "true freedom".
"My Pakistanis, by the time these words reach you I would have been detained under an illegitimate case," he says in the video.
"One thing should become clear for all of you from this is that fundamental rights in Pakistan, the rights given to us by our constitution and democracy, have been buried."
BDST: 1259 HRS, MAY 10, 2023