BAGHDAD (Reuters) — Bombings in Shiite areas of Baghdad and in northern Iraq killed more than 35 people on Wednesday, after weeks of violence by Sunni Islamist insurgents determined to set off sectarian confrontations.

Tensions between minority Sunni Muslims and the Shiites who now lead Iraq are at their highest since American troops pulled out in December 2011, with relations coming under more pressure by the day from the largely sectarian conflict in neighboring Syria.

A string of car bombings hit Shiite neighborhoods across Baghdad on Wednesday evening, including one outside a cafe and another at a market, killing at least 22 people and wounding dozens more, the police said.

“I saw a bright flash, followed by a strong explosion that shook the building,” said Jabar al-Rubaie, a police officer at the scene of a bombing in the Sadr City district in Baghdad. “Glass was shattered everywhere. People immediately ran to the scene and started evacuating the wounded and the dead.”