ISTANBUL — In the latest of a series of attacks on the Turkish military, a remote-controlled bomb killed 5 people and wounded 15 on a busy highway in Istanbul early Tuesday, the governor’s office announced.

While there was no immediate claim of responsibility, Turkish news reports suggested that the attack might have been carried out by the Kurdistan Workers’ Party, an armed separatist group seeking autonomy in southeastern Turkey that the authorities here, along with the United States and the European Union, consider a terrorist organization. The group has been fighting the Turkish state since the 1980s, and more than 40,000 people have been killed in the conflict.

“As Istanbul people, we will hold firm against terror that aims to create an air of anxiety and hopelessness,” Huseyin Avni Mutlu, the Istanbul governor, said. “We will do everything in our capacity to bring the perpetrators of this crime to justice.”

According to witnesses and police investigators, the explosion took place during the morning rush hour in the city’s Halkali district, as a military shuttle bus traveled between a residential compound and offices that include the military police headquarters.

The dead included the 17-year-old daughter of an officer, a statement from the governor’s office said, adding that the bomb, planted in advance, had been detonated by cellphone. Television news images showed the bus with shattered windows and severe damage to the rear.

A spate of recent assaults have been ascribed to Kurdish separatists, including an attack on a military outpost in the southeast two days ago that killed 11 soldiers, provoking a public outcry. This month, a bomb attack wounded 15 people on a military shuttle bus.

The attack on Tuesday also followed a warning by the separatist group that it would carry out strikes in cities across Turkey.

Nihat Ali Ozcan, a Turkish terrorism expert, said the increase in attacks was a reaction to the government’s failure to meet Kurdish political expectations, even though the authorities say they are expanding Kurdish rights and broadening democracy.

The current government is the first to broadcast Kurdish television programming and to allow private Kurdish language instruction. But Prime Minister Recep Tayyip Erdogan has been criticized by some intellectuals and Kurdish activists for not pursuing broader measures, including a comprehensive amnesty to persuade militants lay down arms, Kurdish language education in public schools and a constitutional recognition of Kurdish ethnic identity.

Speaking hours after Tuesday’s attack, Mr. Erdogan called for calm and for parliamentary support for his party’s political efforts, which are referred to as the Kurdish opening.

“We will not compromise on democracy and efforts for national unity and brotherhood,” Mr. Erdogan said. “If we give up the opening, you can be sure that the winners will be the war and terror barons as well as the arms dealers, vampires who feed on the blood of the youth. We will not allow this happen.”