CAIRO – Islamic militants unleashed a wave of attacks in Egypt’s northern Sinai on Thursday, hitting a military checkpoint and killing 15 soldiers there while near-simultaneous attacks elsewhere in the volatile stretch of the peninsula left three civilians dead, officials said.

The attacks were the latest in a series of complex assaults and ambushes in recent months despite a large-scale military campaign that has tried to suppress the growing insurgency in northern Sinai, which borders Israel and the Gaza Strip. The deadliest of Thursday’s attacks mirrored past ones, suggesting careful planning by the militants.

The attack on the military checkpoint south of the town of Sheikh Zuweid killed 15 troops and wounded at least 19, said the officials, speaking on condition of anonymity because they were not authorized to talk to the media.

In four other attacks, also near the same town, three civilians were killed and 13 were wounded. The other attacks appeared to have been aimed at diverting attention from the main assault on the checkpoint, they said.

The military’s casualty toll could be higher, however, since the attackers also seized two armoured vehicles at the checkpoint, possibly taking hostage an unknown number of soldiers inside the vehicles. Later, a helicopter gunship caught up with the two vehicles, rocketing one of them. The vehicle was destroyed and everyone inside it was killed, but the second one got away, the officials said.

The attackers, however, failed to capture a U.S.-made Abrams tank because its crew drove it to another army checkpoint as the attack was underway, they said.

Attacks mainly targeting Egyptian security forces have spiked since the 2013 military overthrow of Islamist President Mohammed Morsi following massive protests against his divisive rule. Most of the large-scale attacks have been claimed by a Sinai-based group that last year pledged allegiance to the extremist Islamic State group, which controls large swathes of territory in Iraq and Syria.

In Washington, the State Department condemned Thursday’s terrorist attack in Sinai and expressed condolences to the victims’ families and Egypt.

“The United States remains steadfast in its support of Egypt’s efforts to combat terrorism in the Sinai and throughout the country, and we will continue to work closely together to address shared threats to regional security,’ said spokeswoman Marie Harf.

On Tuesday, President Barack Obama released military aid to Egypt suspended after Morsi’s 2013 ouster, in an effort to boost Cairo’s ability to combat the extremist threat in the region.

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Associated Press Writer Bradley Klapper in Washington contributed to this report.