IS extremists killed 12 civilians in a suicide car bomb near the Turkish border crossing adjacent to Kobane, according to a monitoring group.
A few hours later, two more car bombs detonated near the border, but there were no immediate details on casualties.
Turkish officials said four victims had died in Turkish hospitals while 96 injured received treatment on the Turkish side of the border.
Claims circulating on the Internet suggested several cars loaded with IS militants passed through the Mursitpinar border crossing in Turkey to make their way into Kobane.
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The governor's office in the border region of Sanliurfa said its information "proves" IS members infiltrated Kobane from Jarablus in Syria.
It added: "Turkish armed forces are monitoring our borders 24 hours as part of security measures."
The Turkish government said video footage taken from Turkish border security units and broadcast by the state-run Anatolia news agency showed a bomb-laden car did not pass through the Turkish border crossing.
Arin Shekhmos, a Syrian Kurdish activist, told AFP in Beirut earlier that IS had entered Syria from Turkey through the Mursitpinar border crossing.
He claimed the IS forces were wearing Kurdish People's Protection Units (YPG) uniforms as a disguise when they entered.
The accusations come amid growing tensions between Syrian Kurds and Turkey.
Turkey says Syrian Kurdish forces who recently made gains in Syria against IS are linked to the Kurdistan Workers' Party (PKK) which for decades has waged a deadly insurgency inside Turkey.
Turkey fiercely rejects the accusations, saying it is making every effort to secure a long border and in turn has accused the West of not playing its part to shoulder the burden of hosting refugees from Syria.